Fixed problem with rocky regions

Version 0.94 fixes a problem with rocky regions sometimes having illegal values that made it so Radiant couldn't even load some maps. For some reason, the rocky regions sometimes had zero width or height, and then later on I divided by that... long story short it should be fixed now.

Buildings without terrain inside of them

Version 0.93 has these additions:

Made terrain not show up inside of buildings. For modders this should be helpful. People that just compile the map and play it will not notice any change, because the buildings have no entrances (yet). This has been one of the hardest parts of the entire project.

Made tree scaling use a normal distribution and added attributes to the "forest" region node in the XML config file, height_percent_mean="0.7" and height_percent_stdev="0.3" for tweaking this.

Added pretty boring graveyard region type that is set to not happen very often by default.

To the right is a picture from inside Radiant showing an area where two buildings are close together, with an alley between them. Some of the terrain patches are selected to show the change that I'm talking about. There is no terrain inside of either building.

Next thing on my todo list is to start adding doors, windows, interior walls, furniture, stairways, basements... to the buildings.