- Print the stream header again
- Fix template button, it should not be translated

rather use no_show_all. This reduces flickering when we show the window

only keyword args should be used

- Use emoji data from a generated dict based on the offical unicode docs,
this makes it easier to update in the future
- Rewrite the emoji chooser
- Add a search field to the emoji chooser
- The emoji chooser is loaded async
- Update to current Unicode 11 Noto theme

- Save all Theme settings to .css instead of the config file
- Add a gajim-dark.css
- Refactor the ThemesWindow