Bugfix in accum texture state handling.
The code assume that the texture environment mode is GL_MODULATE but this state can be arbitrarily changed by client code without being restored.
Bugfix in accumulation buffer resizing for idle AA.
In linux, eqPly idle AA is not working because the pvp used to rendered the quad during buffer accumulation and display is not updated when the FBO is resized.
Merge branch 'accum_fixes' of https://github.com/hernando/Equalizer
Merge cleanups: pimpl for Accum, documentation, correctness