Refactored FlxNapeState into FlxNapeSpace

Previously it was impossible to use nape integration in conjunction with FlxUIStates, by refactoring FlxNapeState into a plugin this is now possible.
Instead of extending FlxNapeState, a FlxNapeSpace.init(); call is now required at the start of the state's create().

napeDebugEnabled has been renamed to drawDebug (consistent with FlxG.debugger.drawDebug).
Merge branch 'dev' into FlxNapeSpace

Conflicts:
 flixel/addons/nape/FlxNapeState.hx
Merge branch 'dev' into FlxNapeSpace

Conflicts:
	flixel/addons/nape/FlxNapeState.hx
Merge pull request #98 from Gama11/FlxNapeSpace

Refactored FlxNapeState into FlxNapeSpace