fixes #97
fixes #51

Add initial loading of qt jdenticon plugin:
https://github.com/redsky17/qt-jdenticon

Currently, the library's functionality has not been integrated
into the rest of nheko.  Next step is to add a configuration
item in the User Settings and use the plugin to generate
avatars for users without their own picture.  These avatars
should be cached in the Cache object.

The room list would be hidden only through window resizing.

fixes #160
fixes #163
fixes #187
fixes #127

fixes #264

fixes #251

fixes #208

- Ghetto disambiguation for the quick switcher
- Fix the Ctrl+K shortcut
- Fix keyboard focus when the quick switcher is closed

fixes #114

closes #46

Minor stylistic refactoring

closes #29