Handles indexed PNGs
Rename PNG test files and add RGBA variations (To be used by TestPNGTextureFromFileNEWT, etc)
Newt PNG test file locations
TestPNGTextureFromFileNEWT: Use new PNG test file locations, add RGBA tests and use alpha in drawable
PNGImage: Cleanup code and reuse scanlineRGBA buffer in indexed mode. Add DEBUG property 'jogl.debug.PNGImage'