FUNCTION: LieTools/AddWgts
USAGE: AddWgts(w1,w2)
SYNOPSIS: AddWgts(w1,w2) yields the (vector-like) sum of two weights
  (The arguments w1 and w2 are lists of rnk(g) numbers.)
CAVEATS: requires a previously initialized global Lie algebra environment.
  (See LieTools[gSetup].)
EXAMPLE: 
> x := LieTools[AddWgts]([1,-2,0],[2,1,-1]);

                           x := [3, -1, -1]

SEE ALSO: LieTools[SubtractWgt], LieTools[AddRts]
