From David Fries, "This updates the CMakeLists.txt instructions for the commands
to make the doxygen documentation."
From Pawel Ksiezopolski, Added example of using osg::TextureBuffer + GLSL to render forest.
Added repolation of the _deadparts stack which would otherwise been invalidatd by the depth sort of particles.
Merge branch 'master' of https://github.com/openscenegraph/osg into dev