Remove dirty from box.

Re Github issue #43

Optimise Box object by removing checks of dirty, which is always true. Deprecate dirty property.
Merge branch 'v1.1.0' of https://github.com/gamelab/kiwi.js into v1.1.0

Conflicts:
	build/kiwi.min.js
	docs/classes/Kiwi.Components.Box.html
	docs/classes/Kiwi.Game.html
	docs/classes/Kiwi.GameObjects.Tilemap.TileMapLayer.html
	docs/classes/Kiwi.Utils.GameMath.html
	docs/data.json