Add configuration interface / API

[Luzifer]

TODO:

• [ ] Add virtual Streamdeck caching-wrapper around physical one
• [ ] Add interface for virtual Streamdeck
• [ ] Add editor mode to interface
• [ ] Add API to "stream" button changes via Socket
• [ ] Add API to set config from editor mode
• [ ] Adjust Wiki pages for breaking changes

Breaking changes:

• interval is now configured as duration, not as int
• Display modules exec and pulseaudio now use rgba instead of color for color configuration