a mix of two changes:
1) remove the DistortedInputSurface interface (now every Surface is Input)2) make the OIT SSBO self-adjustable in size
Finally properly fix the flashing on ARM Mali T880 GPU.
The flashing is caused by a 'full pipeline flush' (see DarkPhoton, https://www.opengl.org/discussion_boards/showthread.php/200754-Flashes-on-ARM-Mali?p=1291679&viewfull=1#post1291679 ). In order to combat it, first introduce the possibility that a single DistortedOutputSurface is backed up by more than one FBO. Then make DistortedScreen be derived from DistortedFramebuffer (which itself is derived from DistortedOutputSurface) and make it contain 3 FBOs, render to them in a circular queue fashion, and blit from a given FBO to the system FBO. The 'more than 1 intermediate FBO' queue prevents the pipeline flush....
Up library requirements to OpenGL ES 3.1 (needed for the upcoming GL_SHADER_STORAGE_BUFFER)
Progress with support for Effect classes.