Merge pull request #6 from p3/master

update from latest upstream
Merge pull request #7 from p3/master

pull latest upstream code
Force uniform update on first use.

In most new programs "ver" is updated through UpdateMatrixVer().
However, when that does not happen a program may end up being
unusable as uniforms are not set correctly.
Add variable to force Desktop GLSL version.

We use this for testing: to run Regal in ES2 mode with GLX.
Merge https://github.com/igor-c/regal glx
Regal::DispatchCode refinements.
Regal::Enum wrapped as struct.