Got the terrain in a pretty good place overall at the world map level,
although there are still some funky things. Need to fix the per-geoform
adjustments (and make them interpolate properly) eventually.

-Peter Mawhorter
Work on fixing various stuff and making some other stuff. Includes
reducing faraway empty patches by making void default to an exposing
block, and some work on geology revision (so far unsuccessful).

-Peter Mawhorter