Better terrain rendering & prefab preview

[dcsobral]

I find it better to have the terrain represented in the 2d map than to rely on moving stuff on a 3d map. On my own 7d2d seed generation, analysis and preview project, seedGen, I have multiple terrain rendering alternatives that could be used:

• Color shade on elevation (drawMap.sh)
• Contour lines (drawContour.sh)
• Glare and shadows on steepness (drawMap2.sh)

I eventually settled on the last one as the most pleasing to the eye.

Prefab preview could also be incorporated by using the prefab's thumbnail in the image. On my project drawPrefabs.sh does that. Alternatively, they could be drawn with different colors to represent what kind of prefab they are. I draw squares around the thumbnails using such a system, with colors selected by prefabZoningColor.sh to account for the zoning of the prefab, though other criteria such as colors for the first prefix of the name (house, store, skyscraper, etc) might work too.