Separate out vertex program objects from fragment program objects and use it.

Given that mShaderObjects only ever expects one copy of a given shader object (leading to lots of "shaderV" and "shaderF"), it made having utility shaders a bit more difficult to incorporate.
This change makes sure the two are separated.  Using this over a multimap largely for readibility.

Also, actually, you know, use this functionality.

--HG--
branch : OPEN-340