- Add theming capability
  - Preset selection
  - Modify each color individually
  - Themes are now defined in assets/ime/theme/ as a json file, which allows for a more convenient way to add custom themes (base for future feature)
- Restructure settings naming scheme and structure
- Add back button functionality in settings
- Add clipboard/cursor tools
- Improve layout measurement and height behaviour
- Fix enter action key bug (#17)