Add a couple more variable types, need to fill this in eventually
Use the right name length value!
Hook glGetProgramResourceIndex
Introduce a bindpoint mapping as part of the pipeline state

* For APIs where the shader namespace/bindpoint (which may be arbitrary
  like 'the Nth texture resource' can be mapped, at each event, to the
  actual API bind point where the object is.
* On D3D11 this is pass-through, on GL this returns the value of each
  uniform.
* This also means GL shader reflection structures are properly immutable
  and the variance in the uniform values is handled elsewhere.
* In future this might need to be expanded to support more complex binding
  methods, where the mapping returns the resource rather than just mapping
  to an integer bind ponit.