Fixed collision maps

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2014-01-29 : v0.6.12
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* Added: drawCollisionMap() now supports Isometric and Staggered maps
* Changed: drawCollisionMap() now requires a collision map parameter
* Changed: setCollisionMap() renamed to getCollisionMap()
* Changed: getCollisionMap() now returns the collision map
* Fixed: Tile properties not being added
* Removed: Map.collision table removed