Collision Layer

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2014-01-15 : v0.2.2
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* Added: Support for basic collision layer
Collision Layer made simpler to use
Custom Layers

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2014-01-16 : v0.3.0
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* Added: Support for converting layers to Custom Layers
* Changed: sti.new()  no longer requires the file extension
Fixed Custom Layer opacity
Update callback for Custom Layers

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2014-01-16 : v0.3.1
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* Added: Update callback to Custom Layers
Fixed typos

copy and paste can be dangerous
Updated map structure

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2014-01-16 : v0.3.2
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* Fixed: a crash if using Tiled 0.9.1
* Changed: map structure to remove "map"table