* Add aria-autocomplete='list' in Textaria
ref: https://www.w3.org/TR/wai-aria-1.1/#aria-autocomplete
* Make detect empty string brefore assign upload description
* Change code elements in keyboard-shortcuts component to kbd
* Add validation for onMuteNotifications
* Make columns-area unscrollable when modal opend
* Make columns-area unscrollable when modal opened
Commit c4a21aa352 scrolls the columns area
when the route changes since the user is likely to want to see the
rightmost column in such cases.
However, redirection is automatic and does not indicate users' intension.
Do not scroll the columns area due to one.
* 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
