[widgets] UI rewrite: Add ManhattanStyle

Begin UI rewrite
[widgets] UI rewrite: Create separate MediaPlayer
[widgets] UI rewrite: New playlist tab
[widgets] UI rewrite: Schedule tabs
[widgets] UI rewrite: Clean style classes
[widgets] UI rewrite: Remove editor from main application
[widgets] UI rewrite: Update OSD with new volume control
[widgets] UI rewrite: Reenable old signal connections
[widgets] UI rewrite: Tab changing using signals
[widgets] UI rewrite: Polishing some views