Previously the front and side faces of random/OSM buildings
had identical texture coordinates. This resulted in the sides
of buildings texture mapping being squeezed or stretched.
This change generates a separate texture mapping for the sides
of the buildings.
Previously there was very limited texture variations
as a given texture index was used for both the wall
and ceiling. Now these can be specified separately,
allowing for more variation in both STG defined and
random buildings.
Requires simgear commit 053bda26a43314a91b01b08cd4617da82f7ab807
Replace random buildings with one using proper instancing.
Also implement more control over rendering of random buildings.
see README.scenery for details.
