Make redisplaying the keyboard faster
- Don't recreate the keyboard widget (and therefore the renderer) all the time
- Cache icon lookups
I'll follow up with a patch to detect icon theme changes but wanted to get that out for review since current squeekboard is quite ugly in e.g. chatty due to the slow switching. Since we don't recreate the widget i expect issues on keymap change, rotation, etc. but since the code for that has yet to be written we can hook this up correctly when there I guess.
Closes: #60 (closed)