Beta 1 ship list

It's very strange to see the word beta in a ship list title, but oh so awesome!

Highlights

Dropped Normalize.css as a dependency, forking some of it and remixing it with our own Reboot for a more stable normalization approach.
Update navbar responsive behaviors to be mobile first, use a new class name .navbar-expand instead of .navbar-toggleable, remove toggler position modifiers (relies on flex utils now), and fix a handful of bugs.
Stabilize some grid behaviors and update the docs.
Updated the grid to drop push, pull, and offset in favor of new .order- modifiers and margin utilities.
Renamed tons of variables (see #22414 (closed) and #22092 (closed)) for a more consistent naming scheme.
Removed remaining cursor: pointers to restore browser defaults and better indicate actions vs hyperlinks.
Renamed flexbox order utilities to better match utility naming scheme of .property-value.
Restored Alpha 5's placement of _custom.scss in our import order.
Rewrote display and responsive utilities to de-dupe a bunch of functionality.
Removed Gruntfile and docs from package manager builds.
Overhauled our color system with new Sass maps, variables, classes, and component variants.
Updated browser support to bring ranges up to more recent versions.
Added a bash script for linting unused variables.
Moved jQuery and Popper to peerDependencies as they're not requirements for every part of Bootstrap.

CSS

#21579: Remove unused Sass variables.
#21590 (closed), #21605 (closed), #21722: Prevent containers from collapsing on themselves in navbars due to mix of auto margins and flex parent.
#21593 (closed), #21651 (closed), #21716: Fix segmented buttons in input groups with simpler flex styles.
#21603: Restore Alpha 5's import order for the _custom.scss file, moving it back to the top before variables and mixins again.
#21621 (closed), #21626: Prevent .navbar-brand from growing too wide.
#21625 (closed), #21633: Don't style give the :focus state of links the same styles as the :hover state in Reboot.
#21648: Remove unnecessary opacity filter from custom forms given dropping of IE9.
#21653: Follow up to Alpha 5's removal of the classes, finish removing list group item heading and text in mixin and variables.
#21660 (closed), #21824: Add flex-wrap: wrap to .navs so they behave like they used to before the move to flexbox.
#21699 (closed), #21826: Add flex-wrap: wrap to button toolbars to restore previous behavior.
#21739: Rename order utilities.
#21740 (closed), #21741: Drop Normalize.css as a dependency; instead fork it and blend those into Reboot.
#21793 (closed), #21796: Fix spacing when using <label>-based buttons in button groups.
#21805: Match line-height to height in progress bars.
#21812: Remove cursor: pointer.
#21821: Improve rendering of navbar toggler icon.
#21825: Followup to Alpha 5—fix the import order for the grid and Reboot builds.
#22039: Remove vendor prefixes from appearance: none.
#22073 (closed), #22087: Remove -hover from the $nav-tabs-active-link-hover-* variables as it no longer applies to the hover state.
#22011 (closed), #22068: Use correct variable for custom select border width calculations.
#22027: Changed the z-index order for sticky and fixed elements.
#21762 (closed), #21965 (closed), #22113: Removed nearly all .hidden-* classes in favor of our newer .d-* display utilities. Rewrote some docs and consolidated CSS, too.
#21836 (closed), #22123, #22125: Update margin/padding spacer variables to remove $spacer-x and $spacer-y, consolidating into just one $spacer and the Sass map.
#22012 (closed), #22124: Move transition and box-shadow mixins to their own files.
#22164: Share color variables from default buttons with outline buttons.
#17573 (closed), #21977: Remove dropdown toggle's outline focus overrides.
#21584 (closed): Remove display: flex from .list-group-items to avoid unexpected layout glitches. Instead, use utilities as needed.
#21927 (closed): Update .nav-justified to fix the broken styles; also update docs examples for <nav>-based variants.
#22154: Update sr-only mixin and class to use latest clipping technique.
#22217: Update inverse table styles to add new variables and styles for accent, hover, and active backgrounds. Also fix their border colors.
#22271: Update grid docs for auto-sizing behaviors, remove position: relative from .container, fix broken only and between mixins, and give .col-auto classes some horizontal padding.
#21650 (closed), #22288: Prevent card images from being stretched due to flexbox bug with intrinsic image ratios.
#21976 (closed), #22007 (closed), #22289: Fix wrapping card decks by correcting their margins.
#22287: Updates $btn- and $input- variables for padding and line-height to be shared like the $input-btn-border-width variable. Also increases $line-height-lg and adds a line-height parameter to the button-size mixin.
#22153 (closed), #22221: Add variables for setting popover content and title color.
#22387: Add .dropdown-item-padding-y variable.
#22386: Add transition to progress bar.
#22392: Fix carousel issues with aspect ratios and transition timing.
#22056 (closed), #22394: Update card outlines to properly style header/footer background and border.
#22135 (closed), #22393: Always apply margin-bottom to cards in .card-columns.
#22403: Remove cursor: not-allowed styles.
#22396: Don't include Gruntfile or docs in package manager builds.
#22433: Fix popover arrow color for bottom position
#22413: Rename variables that applied border-color to include color in their names
#22573: Add shim for "new" HTML5 structural elements
#22539: Remove unused variables
#22630, #22644: Dropdown must be displayed in position static for navbar, to override Popper CSS
#22579: Restore box-shadow to progress bar background when enabled.
#22564: Rename $navbar-*-toggler-bg to $navbar-*-toggler-icon-bg.
#22741: Rename $card-border-radius-inner to $card-inner-border-radius.
#22740: Fix overflowing text in Cards with word-wrap: break-word.
#22414 (closed), #22805, #22806, #22807, #22808, #22809, #22810, #22814, #22818, #22843: Rename dozens of variables for consistent naming scheme.
#22092 (closed), #22828, #22829: Rename card and popover variables to better match the naming scheme established by modals.
#22836: Replace existing color system with new Sass maps and variables, new color values, and improved generation of component variants.
#22940: Removed previously added $grid-gutter-widths Sass map. It generated the wrong code and is no longer the method we'd prefer for setting custom grid gutters. A replacement will come soon.
#22943: Reduced browser support further to focus on modern ones with full support for our key features (e.g, flexbox).
#22942: Updated the grid to drop push, pull, and offset in favor of new .order- modifiers and margin utilities.
#22949: Redesign blockquotes and remove .blockquote-reverse.
#22950: Overhauled card variants, dropping all the existing mixins and modifier classes and replacing them with .bg-, .text-, and .border- utilities for greater flexibility.
#22961: Moved float and embed utilities to their own files, removing _responsive-helpers.scss in the process.
#19353 (closed), #22966: Add ability to customize active background and border on button mixin.
#22998: Remove box-shadow from .btn-link:focus
#23044: Remove ::first-letter and ::first-line selectors from print styles

JS

#21697: Use existing keycode constants in dropdown.
#21709: Correct reference to Direction.PREV constant.
#20620 (closed), #21756: Allow tab JS to work with list groups.
#21572 (closed), #21578: Fix background dismissing of dropdowns on mobile.
#21328 (closed), #21615: Allow # in data-targets to avoid throwing errors.
#19774 (closed), #21788: Get HTMLElement.offset* by getBoundingClientRect().
#22138, #22251: Add ability to create accordions without using cards.
#21668: Carousel - Add attributes from and to for Slid and Slide events
#22272, #22297: Collapse - do not prevent event for input and textarea
#22276: Fix different tooltip offset when hovering
#21743: Fix JS components console error "Error: is transitioning"
#22316: Popover + Tooltip - fix error when content or title is a number
#21807: Tabs/Scrollspy/.nav/.list-group/.active independent of markup
#18441, #22337: Rewrite Modals.setScrollbar() and Modals.resetScrollbar() to properly handle padding-right of body and fixed elements
#22398: Prevent default for ESC in modal.js
#22400: Only change aria-pressed if it's not an input-based radio or checkbox group
#22397: Fix collapse.js aria-expanded behavior
#21535: remove dropdown.js reliance on roles and fix keyboard navigation
#22426, #22482: Replace dropdown backdrop hack with cleaner JS-only hack
#22442: Fix carousel "hover" behavior on touch-enabled devices
#22481, #22483: Add iOS hack to tooltips
#22499: Fix Toggle buttons don't honor [disabled] or .disabled
#22480: Fix typo removeData for Tabs plugin
#22444: Remove Tether for Popper.js
#22640, #22664 : Use Popper.js to align dropdown menu instead of using css with important
#22681: Use Popper.js to manage arrow position for Tooltips/Popovers
#23162: Update Popper.js to 1.11.0
#22687: Placement auto for Tooltips and Popovers
#22713: Collapse support multi target
#23182: Add semicolon for our dist files in stamp.js

Docs

#21565: Update migration docs to mention badges, not tags.
#21566: Remove IE9 and SVG callout.
#21664: Correct breakpoint value in responsive utils docs.
#21673: Document example of <hr>s in alerts.
#21674: Document example of linked badges.
#21746: Specify reliance on .cards for accordion behavior.
#21813: Fix body padding in Dashboard and Jumbotron examples.
#22004: Remove Normalize.css callout.
#22078: Update broken/redirected links.
#21938: Fix data-pause documentation for carousel
#21726: Fix accordion behavior with JQuery interface
#22246: Add missing v4 docs for tooltip/popover methods
#22373: Add inserted event for Tooltip and Popover
#22321: Add explicit aria-label to placeholder-only inputs
#22401: Remove incorrect role="tabpanel" from navs docs
#22405: Remove inappropriate role="listbox" from carousels
#22445: Use actual <button>s in copy buttons
#22440: Rewrite getting started/accessibility docs
#22461: Add dropdown menu accessibility callout and fix example
#22455: Port button group accessibility callout from v3 to v4
#22500: Documentation cleanup (inc. use of <input ... readonly> for static form controls example)
#22472: Styling and accessibility clarification for navs documentation
#22364: Add missing <main> element to documentation
#22574: Add explicit role="main" to <main> elements
#21490 (closed): tooltips/popover must be hidden before their corresponding element is removed from the DOM
#22641: fix tooltip documentation page missing classname prefix "bs-" to tooltip top
#22423: Add docs for using Bootstrap with Webpack.
#22848: Docs: accessibility and IE fixes for SVG-based top navigation
#22961: Rearrange responsive embed and float utilities.
#23060: Add badge counter example and accessibility advice

Build tooling

#21591: Fix incorrect docs.min.js bundle source for hosted docs.
#21816: Move htmllint task to npm scripts.
#21918: Update to CleanCSS v4, etc.
#22047: Refactor QUnit test page.
#22066: Move jekyll task to npm scripts.
#22167: Update to postcss-cli v3, etc.
#22168: Config tweaks. Move Travis to Node v7. More ESLint rules.
#22218: Update to jQuery 3.2.0, etc.
#22233: Config tweaks.
#22464: Fix running test on iOS with Saucelabs.
#22045: Move all remaining tasks to NPM.
#22477, #22534, #22517: Fix regressions caused by #22045 and update docs about the build system.
#22496: New watch task
#22554: Remove log from WEBrick during js-test-cloud
#22822: Qunit update + fix Saucelabs test on Edge
#22954: Add bash script to lint for unused variables.
#23091: Start testing on Node v8.
#23094, #23099: Update dependencies and switch to using NPM lockfiles.
#23264, update devDependencies.

Packaging

#21580: Update readme test badge to point to v4-dev branch.
#23244: Move jQuery and Popper to peerDependencies.