palette is now a UIList
nodes can be collapsed/expanded using right mouse click
copy subtrees using SHIFT
link subtrees using SHIFT, does not work fully
Merge remote-tracking branch 'upstream/develop' into behavior
updated to latest changes
Tasks are now injected
Merge remote-tracking branch 'upstream/develop' into behavior

Conflicts:
	engine/src/main/java/org/terasology/logic/players/MenuControlSystem.java
fixed bt editor layout
editor now opens using F5
refactored Task and Interpreter
Stopping a task now stops all tasks, that were started by the task.
Merge remote-tracking branch 'upstream/develop' into behavior

Conflicts:
	engine/src/main/java/org/terasology/logic/behavior/nui/BehaviorTreeEditorSystem.java