Implement non-square matrices, and make a few type improvements.  Cleaned up a few old issues. Added two tests.

Details
 - added all the new non-square types
 - separated concepts of matrix size and vector size
 - removed VS 6.0 comments/workarounds
 - removed obsolete concept of matrix fields



git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@20436 e7fa87d3-cd2b-0410-9028-fcbf551c1848