Index ranges

Index ranges are not allowed on scalars, matrices or tensors, but subsets of vectors or string variables may be eliminated by including an index range. For example:

`DESTROY X[5:25:5] Y[IDX] S[1:5] T[2][1:10]`

will eliminate elements `5, 10, 15,` and `25` from vector `X`. If `IDX` is a vector, then `Y[IDX[1]]`, `Y[IDX[2]]`, … `Y[IDX[#]]` will be eliminated. If `S` is a string variable, characters `1` through `5` will be eliminated. If `T` is a string array variable, then characters `2` through `10` of string `2` will be eliminated.

Expanded names
Destroy entire classes of variables