Added support for IQM int/float encoded blend indices and weights. This makes it possible to import IQM files from Noesis.

I've updated both gl1 and gl2 renderers so they can import IQM files exported from Noesis.  Although the official IQM spec recommends indices and weights encoded as bytes, Noesis exports them as ints and floats (respectively).  This patch allows the IQM loader to account for both cases.