"state.matrix.modelview[0]" to the equivalent "state.matrix.modelview".
Per ARB_vertex_program, the "[0]" syntax is supported only when
EXT_vertex_weighting or ARB_vertex_blend are supported."
part of prep for supporting both Matrixf (float) and Matrixd (double).
Added osg::Matrixf::glLoadMatrix() and osg::Matrixf::glMultiMatrix() methods
and changed corresponding usage of glLoad/MultMatrixf() calls across to use these
methods. Again prep for support Matrixd.
Fixes for VisualStudio 6.0 compile.