Enrich the Multiblur app.
New 'glClearColor' and 'glClearDepthf' APIs in OutputSurface. This fixes the 'transparency' regressions from last commit.
Speed up shaders (both compilation and execution) by explicitly enabling only the needed effects.
Change the the render() API!
THis introduces some regressions with the Effects3D app.
Major: change of API.
Split DFramebuffer into Framebuffer and Screen; introduce the 'DistortedInputSurface' and 'DistortedOutputSurface' interfaces.
Some fixes for issues discovered by the Multiblur app.
Beginnings of the 'Multiblur' app.