Change random generation of lakes to something more sensible
Merge branch 'master' of https://github.com/SJakobsen/DIM3-Team-M
Improve random lake generation even further

Now the depths can span randomly, as opposed to single bumps,
so that the lake looks much more realistic.
Merge branch 'master' of https://github.com/SJakobsen/DIM3-Team-M