I believe the tests are failing because the shortcut only works
when you select a channel on the channel dropdown. So I updated the testcases to do this.
The JoinLastClosedChannel code was using the joinedChannels list instead
of the closedChannels list. Fixing this bug made the Ctrl+Shift+t
shortuct work as expected.
Added a list to the ChannelManager class that tracks
which tabs I closed. Works like a stack, where it adds to the end
every time I close a tab. Then added a function that uses
this list to open the last closed channel, and added a shortcut inside of ChatOverlay,
similar to how jmeng implemented shortcuts.
Code is currently untested.
As we are finally pushing updates for this database, this adds a minimum
level of guarantee that a client will request a new version (without
having to worry about multiple levels of server-side caching).