* Render a colored dot for colored tags
* Improve spacing and positioning, especially on 2x screens
* Add scss map for tag colors in light/dark scheme
* Add support for compact/comfortable in tag selector
* Restyle filter box, add a placeholder and a new icon
* Opt-in for light and dark color schemes
* Convert scss variables in _light.scss to css variables
* Add _dark.scss for dark color scheme
* Remove unused, theme-related variables
8337b7ec1 fixed a regression in the Reactified tag selector that
prevented it from using GTK theme background colors on Linux, but it
accidentally made the background gray by default. This restores the
default white background.
Fixes#1684
- Added icon-button UI code for the menubutton
- Upgrade to React 16 to allow non-standard attrs, such as `tooltiptext`
to support XUL tooltips
- Add i18n support for React UI elements
- Update tests for reactified tag selector
