Add parsing of 'extra' nodes in Collada. Register content as JSON string in ISceneNode.userData.

We need to support Object data structure in DataProvider so we can (almost) directly map the <extra> node from XML to Minko userData.
ColladaImage fill the name property of TextureResources
Merge remote-tracking branch 'refs/remotes/origin/feature/user-properties' into dev-3
Fix camera deserialization
Call to ParserOptions.materialFunction in ColladaMaterial.
Fixed warning.
Moved calls to ParserOptions.materialFunction in InstanceGeometry and InstanceController.
Merge remote-tracking branch 'refs/remotes/origin/material-function' into dev