FUNCTION: LieTools/SubtractWgt
USAGE:  SubtractWgts(w1,w2);
SYNOPSIS: SubtractWgt(w1,w2) yields the (vector-like) difference w1-w2 of two weights
EXAMPLE: 
SubtractWgt([1,0,2],[1,1,1]);
                              [0, -1, 1]

SEE ALSO: 
