Updated terrain generator (please read this)

Design is slightly more intelligent.  Shapes of terrain types aren't
quite rounded yet, but lower elevation elements (water, dirt, grass)
tend to cluster closer together and higher terrain elements (stone,
sand) tend to stick together more (although its still dominantly sand).
I think its also guaranteed to generate wood and stone in each map, but
its only lightly tested.  If you ever get a map without stone or wood,
let me know.  Similarly, if you ever get a map that prints out a number
in that huge jumble in the debug log that is less than 0, or greater
than 1, let me know what the seed was.