* feat(components/media_gallery): Responsive images

* fix(components/media_gallery): Link to image URL

* Remove unused column_collapsable.js
* Remove old styles
* Extract `> div`  style to independent class

ref https://tc39.github.io/proposal-decorators/

(This patch has been merged as bugfix and reverted, but still valuable as
improvement)

Previously, we've attached IntersectionObserver twice for boosted statuses:
wrapper Status and wrapped Status. but wrapped Status don't need to manage
intersection and visibility by itself, because it's a part of wrapper Status.

* Revert "Bump version to 1.4.4"

This reverts commit 1585b0c6.

* Revert "Fix conversations (fixes #3869) (#3870)"

This reverts commit 15b43f55.

* Revert "Fix streaming server. Redis connection subscribe for each channel. (#3828)"

This reverts commit d8ec8328.

* Revert "Filter direct statuses in Status.as_home_timeline (#3842)"

This reverts commit bab5a182.

* Revert "Fix RemoteFollow behavior (#3868)"

This reverts commit a20cf3b6.

* Revert "Update fabricator for MediaAttachment to attach a file according to type (#3862)"

This reverts commit 356df7ae.

* Revert "Upgrade React Router (#3677)"

This reverts commit 8f03fdce.

* Revert "Do not call setState from unmounted component (#3853)"

This reverts commit 1fc6cb49.

* Revert "Replace TextIconButton for SensitiveButton to IconButton (#3759)"

This reverts commit eb832e88.

* Revert "Fix RTL detection on Ruby side (#3867)"

This reverts commit b16b6935.

* Revert "i18n: Fixed typo in Polish translation (#3864)"

This reverts commit da6fa029.

* Revert "Don't attach IntersectionObserver for wrapped statuses (#3863)"

This reverts commit 94ad0706.

* chore(yarn): Remove react-router

* chore(yarn): Remove react-router-scroll

* chore(yarn): Remove history

* chore(yarn): Add react-router-dom

* chore: Remove usages of react-router-scroll

* refactor: Upgrade to react-router-web

* refactor: Use fork of react-router-scroll

This reverts commit 2ddea9a6c8d39fc64b7d0b587f3fbda7a45a7fa2.

* fix: Issues mentions in the PR feedback

Stop an executing task if the component already unmounted.

This fixes a bug that sometimes boosted statuses being hidden on scrolling.

Previously, we've attached IntersectionObserver twice for boosted statuses:
wrapper Status and wrapped Status. This will call intersection handler twice,
so this may results race condition...probably.

* Unread indicator was invisible behind column header, adjusted

* Unread indicator now a CSS pseudo-element

* Adjust flex

- Use plaintext
- Strip out URLs
- Strip out mentions
- Strip out hashtags
- Strip out whitespace from "overall" count
- Consistent between JS and Ruby

* Add regex filter on the community timeline and the public timeline

* correcting

* Adjust the height of header buttons

* Remove trailing spaces

* Remove trailing spaces

* Solve some code duplication

* reset the state of the locale files in app/javascript/mastodon/locales

* adjust to upstream

* adjust to upstream

* change keys of locale settings

* Add react/no-string-refs ESLint rule

* Add react/jsx-boolean-value ESLint rule

* Add react/jsx-closing-bracket-location ESLint rule

* Add react/jsx-indent ESLint rule

* Add react/jsx-curly-spacing ESLint rule

* Add react/jsx-equals-spacing ESLint rule

* Add react/jsx-first-prop-new-line ESLint rule

* Add react/jsx-no-duplicate-props ESLint rule

* Add react/jsx-tag-spacing ESLint rule

* Add quotes ESLint rule

* Add jsx-quotes ESlint rule

* Sort ESLint rules

* Allow mounting arbitrary columns

* Refactor column headers, allow pinning/unpinning and moving columns around

* Collapse animation

* Re-introduce scroll to top

* Save column settings properly, do not display pin options in
single-column view, do not display collapse icon if there is
nothing to collapse

* Fix one instance of public timeline being closed closing the stream
Fix back buttons inconsistently sending you back to / even if history exists

* Getting started displays links to columns that are not mounted

* Change PureComponent to ImmutablePureComponent

Change PureComponent to ImmutablePureComponent in AttachmentList.

* rm React.

Fix warning for ESLint (jsx-a11y/href-no-hash).

I've found this issue when I clicked replies to muted user on the timeline.

Properties I've removed in here were added with lazy loading using
IntersectionObserver (8e4d1cba), but those statuses are not need to be
tracked anyway because it will be rendered as only empty div.