Memory Leak for repeated set() parameter calls #132

Repeatedly calling .set() for a Parameter and VectorParameter, when set is non-uniform, overrides the StaticField previously there. Since this is a common occurance in the python script (set constant/static/uniform values for EQ, then have non-uniform for driving simulations or grid searches/loops) with the same world and/or ferromagnet, this can build up considerable memory loss (many GB in only a few iterations).