A few things remain to do:
* The binding between a uniform block in a shader program and a buffer indexed target number is fixed, like a vertex attribute binding. This is too restrictive because that binding can be changed without relinking the program. This mapping should be done by name in the same way that uniform values are handled i.e., like a pseudo state attribute;
* There's no direct way yet to query for the offset of uniforms in uniform block, so only the std140 layout is really usable. A helper class that implemented the std140 rules would be quite helpful for setting up uniform blocks without having to link a program first;
* There's no direct support for querying parameters such as the maximum block length, minimum offset alignment, etc. Having that information available outside of the draw thread would make certain instancing techniques easier to implement."
Removed EXT postfix of FrameBufferObject functions, and added support for checking non EXT versions frame buffer object GL functions.
Introduced usage of OSG_GL*_FEATURES to avoid some #if #else #endif code blocks.
Using a submissions from Paul Martz as a guide added perliminary GL3 support to a range of OSG classes
