Added preliminary wildcard support for dihedral types 1, 2, 3.

The lookup works correctly but for some reason an RBDihedralForce
cannot be created with the parameters. To replicate error:

pdb.set_trace() after line 972 in GromacsTopologyParser.py
the created 'newDihedralForce' returns as nonetype.

Probably some silly error that I'm missing.