Add glUniform2fv to Glow JSON restriction file.
internal/gl: regenerate using Glow and fix import paths.
Allow gfx.TexCoord as shader uniform inputs; helps #24

We do not need to add gfx.Color because it was already (incorrectly)
there earlier.
Mention how shader Inputs map to GLSL uniforms; helps #24
Merge v3-dev branch into v3-texcoords-colors

I meant to use v3-dev as the base, sorry.
Improve package documentation significantly.
Allow gfx.TexCoord as per-vertex-attributes; Fixes #24
Merge pull request #25 from azul3d/v3-texcoords-colors

Support shader input/vertex attribs: gfx.TexCoord and gfx.Color