Fixes#2220
This drops the ability to shift+click on “Back” to get back to a pinned
column, but that was inconsistent, broken, and undocumented.
This also brings us slightly closer to upstream.
Using an emoji map was completely unnecessary in
the first place, because the reaction list from
the API response includes URLs for every custom
emoji anyway. The reaction list now also contains
a boolean field indicating whether it is an
external custom emoji, which is required because
people should only be able to react with Unicode
emojis and local custom ones, not with custom
emojis from other servers.
Reactions will be backported to the vanilla
flavour, which requires all related settings to
be accessible from the vanilla settings page
rather than the glitch specific settings modal.
This adds an extra item to the local settings for
specifying the number of reactions shown in toots.
The detailed status view always shows all
reactions.
