Make control group hotkeys configurable

- Split control groups management to its own interface
- Add hotkeys for selecting, creating, adding to and combining with control groups
- Add a ControlGroups widget to manage the player interaction

mods/d2k/rules/world.yaml

@@ -4,6 +4,7 @@
 	ScreenMap:
 	ActorMap:
 	Selection:
+	ControlGroups:
 	MusicPlaylist:
 		VictoryMusic: score
 		DefeatMusic: score