Note, this required adding a unsigned int context ID to the osg::isGLUExtensionSupported(,)
and osg::isGLExtensionSupported(,) functions. This may require reimplementation
of end user code to accomodate the new calling convention.
extra pass to doing tri stripping in the osgUtil::Optimzer.
Added validity checks into osg::TexEnvCombine to catch eronous enumarant values.
Improved the efficient of CullingSet's handling of new transforms.
Added a copy shared subgraphs and subdivision code into osgUtil::Optimizer.
