Lower requirements - now only OpenGL ES 3.0 is required; if running on such platform, OIT part of the API ( which is the only one which actually requires 3.1) is switched off.
Minor.
Remove width & height from InternalSurface and move it to InternalOutputSurface.
Hide the InternalSurface class inside its package.
Move the 'pre-multiply mesh before applying any effects' thing from [(Xsize of texture, Ysize of texture) x Mesh's zFactor] to Effects.setStretch(sx,sy,sz)
Correct the Legal notice.
Rename all the classes that are not exported to application to 'Internal'