Implement ImageDataFactory::createImmutableImageDataRegion native. Fixes #541.
Remove WIP comment
Set mutable field in the destination ImageData object
Add test that creates an image from a region of another one
Print "FAIL" when failing to load the image, so the casperjs script can catch the failure
Merge pull request #542 from marco-c/createImmutableImageDataRegion

Implement ImageDataFactory::createImmutableImageDataRegion native