List Commands Library for 50g

[DavidM]

After trying out DOCOMB and DOPERM on a few tests, I've come to the conclusion that it would be better to have them return their results in list form instead of as individual items on the stack. Exploding the list (if needed) is trivial, but imploding it after the fact is more problematic, especially if you aren't sure in advance how many items will be in the result. So it makes sense to me to return the results as a list instead.

That also makes the commands more like the built-in ones, so that's a plus. I draw the line at returning no results, though. DOCOMB and DOPERM will return an empty list instead of nothing if there are no results.

The next release will have these changes.