Material design + view related refactoring

 - Material design
 - New light theme
 - Theme switcher
 - Full layout refactoring
 - Dialogs refactoring
 - Search view in track list

TODO:
 - ~~Fix switch "track" color (now it's invisible when switch is of in light theme)~~
 - ~~Scroll bar missing in track list~~
 - Upload new screenshots
 - Found out what's wrong with unit tests and fix them
Lint suggests to use SharedPreferences.Editor.apply() instead of commit() for better performance, apply will happen in background thread, commit in caller (Ui) thread, I think it's better to create an issue for that to fix WAILSettings fully