Add the possibility to customize the primary and accent colors.

[roschlau]

It would be cool to set the colors of the background (primary) and the dial wheel (accent) inside of the app to your own preferences.

• [ ] Look for library for color picker
• [ ] Build UI and save chosen colors in preferences
• [ ] Set primary and accent color on startup according to preferences
• [ ] Test

[roschlau]

Preliminary research suggests it isn't possible to switch out the actual colorPrimary and colorAccent attributes at runtime, as themes are immutable. This leaves only two options: Restrict the available choices to a few predefined themes which can be applied at an Activity restart before setContentView, or manually inject the colors into the views, bypassing colorPrimary and colorAccent altogether. I'd prefer the second option, as there are only very few views that would have to be injected.

GreenMatter would have been a possibility, but as of now doesn't seem to work on Android M.

Sources: Stackoverflow questions

[roschlau]

Spectrum looks good for providing the color picker.