The enum is finally completely reimplemented for specific cases with
proper values (Mesh attribute types, index types, pixel types, ...). The
rest currently remaining in TypeTraits.h is used only in Mesh and
AbstractShaderProgram, probably will be moved there.
Desktop OpenGL and OpenGL ES 2 support can be switched using CMake
TARGET_GLES option. All functionality not supported in ES is marked in
documentation.
If targetting OpenGL ES, GLES2/gl2.h is included instead of GLEW.
Mesh class now uses VAOs only in desktop OpenGL, in ES the buffers are
bound on each draw call.