Deleting water bodies

I've added a mouse tool for deleting water bodies. This feature will be available in L3DT release 2.2a.

I'm not willing to give an ETA for release 2.2a, as my first estimate for the 2.2 release date missed the mark by around seven months. Release 2.2a shouldn't take that long, but I don't believe in a deterministic universe - anything could happen in the mean-time.

OK, maybe not a violation of the 1st law of thermodynamics…but almost anything.