Add more building types

[PatrickMurphy]

Right now it really can only generate sky scrapers

Need to make:

• Houses (one or two squares with roof)
• Large house (more complicated, sometime 2 stories looks nicer)
• warehouse/industrial (large short buildings)
• stores (gas station size etc)
• more?

[PatrickMurphy]

Added a second type, determined by population density, makes good looking downtown areas for now