unpackUnorm4x8 requires ARB_shading_language_packing

Signed-off-by: Nick Minkler <sleaker@gmail.com>
Fix CubeMesh handling.

Add VertexAttribIPointer, interface out the VertexAttribPointer as there is more than 1 possibility.

Signed-off-by: Nick Minkler <sleaker@gmail.com>
Merge pull request #9 from Sleaker/master

Add necessary alternative VertexAttribPointers and Interface them out.