* 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.

Since long lines may overflow and cause the status-list horizontally scrollable,
I added `overflow: hidden` to placeholder contents to prevent it.

* refactor(components/status_list): Lazy load using IntersectionObserver

* refactor(components/status_list): Avoid setState bottleneck

* refactor(components/status_list): Update state correctly

* fix(components/status): Render if isIntersecting is undefined

* refactor(components/status): Recycle timeout

* refactor(components/status): Reduce animation duration

* refactor(components/status): Use requestIdleCallback

* chore: Split polyfill bundles

* refactor(components/status_list): Increase rootMargin to 300%

* fix(components/status): Check if onRef is not defined

* chore: Add note about polyfill bundle splitting

* fix(components/status): Reduce animation duration to 0.3 seconds

Focus the submit button when confirmation modal is opened.

Also, changed cancellation link to button.
This makes the meaning clearer.

original: https://github.com/tootsuite/mastodon/pull/2618

* Add semi to ESLint rules

* Add padded-blocks to ESLint rules

* Add comma-dangle to ESLint rules

* add config/webpack and storyboard

* add streaming/

* yarn test:lint -- --fix

* refactor(components/status_list): Avoid quering scrollTop if not necessary

* refactor(components/dropdown_menu): Do not render items if not expanded

* refactor: Cherry-pick react-motion imports

* refactor(compose/privacy_dropdown): Do not render options if not open

* refactor(components/column_collapsable): Do not render children if collapsed

* Add account media gallery view to web UI

* Link media view from account dropdown

* Adjust link

* feat(eslint): Set react/jsx-no-bind: error

* refactor(notifications/setting_toggle): Do not use bind

* refactor(components/dropdown_menu): Do not use bind

* refactor(components/autosuggest_textarea): Do not use bind

* refactor(compose/privacy_dropdown): Do not use bind

* refactor(compose/upload_form): Do not use bind

* refactor(components/status): Do not use bind

* refactor(components/onboarding_modal): Do not use bind

* refactor: PR feedback

* chore(notifications/setting_toggle): Lint

* refactor: PR feedback

* Always set `overflow: auto` to allow scroll just after opening
* Remove bounce animation which may cause unintended behavior due to max-height
* Use CSS transition instead of react-motion
* Some CSS refactoring including className changing

* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Conversation muting - prevents notifications that reference a conversation
(including replies, favourites, reblogs) from being created. API endpoints
/api/v1/statuses/:id/mute and /api/v1/statuses/:id/unmute

Currently no way to tell when a status/conversation is muted, so the web UI
only has a "disable notifications" button, doesn't work as a toggle

* Display "Dismiss notifications" on all statuses in notifications column, not just own

* Add "muted" as a boolean attribute on statuses JSON

For now always false on contained reblogs, since it's only relevant for
statuses returned from the notifications endpoint, which are not nested

Remove "Disable notifications" from detailed status view, since it's
only relevant in the notifications column

* Up max class length

* Remove pending test for conversation mute

* Add tests, clean up

* Rename to "mute conversation" and "unmute conversation"

* Raise validation error when trying to mute/unmute status without conversation

* selectively Revert "Fix regressions from #2683 (#2970)"

This reverts commit 72698bc3.

* Revert "Handle hashtags in spoiler_texts (partial fix for #699) (#2683)"

This reverts commit e2491680.

Resolves #2515