License statement text corrected; compiler warnings caused by Bison 2.41 disabled for MSVC; a few other compiler warnings on 54-bit Windows eliminated by appropriate type cast
Wrong license statements corrected in several files.
Copyright and license statements added in XSD and GLSL files.
Copyright year updated in some files.
Obsolete documentation files removed from DrawResources.
Extend OpenGl_Context to provide GL2.0 core functionality
Added 'glext.h' header provided by Khronos group with definitions
and GL functions' types.
Added OpenGl_GlCoreXX structures with function list
to appropriate GL core functionality.
Fixed memory leak in OpenGl_Context destructor.
Eliminate inclusions of gl.h header
Use OpenGl_GlCore11.hxx instead.
Removed obsolote M_PI redefinitions.
Slightly cleaned up included headers.
Reuse definitions from glext.h
OpenGl_ArbVBO and OpenGl_ExtFBO originally provide own definitions
for OpenGL extensions.
