Fix handling when there are too few trees. Also add debug tool to remove trees.

Some README updates.

Track preserve cells to avoid repeatedly getting same dialog.

Add dialog when there's a significant amount of preserve. Plus some thoughts on avoiding gaming.

Add dialog when player reaches certain thresholds for preserves.

Add attributions for sound effects.

Add little ponds and improve water status messages. No longer render water cells as "Water Oak." (Oak is the value of the enum when set to zero.)

Improve water generation. ?Fix bug cause incongrous coastlines (i.e., coastline that doesn't line up with surrounding tiles). ?Randomly choose between open water tiles.

Keep ordered list of FPS. Keep a second list in original order.

Tweak odds of tree spawning. Reduce the odds in a preserve so it's just double the regular rate..