Make sky color more natural
Add fused versions of terrain

These models have all the xrefs inlined and all the objects fused into one large object to the extent that it's possible
Add fused terrain and new app 3b that has more tiles than 3

Details of which tiles in 2 are fused are in readme.txt.  All of the tiles in 3 and 3b are fused.  Fused tiles render faster, but require more memory.  3b has the maximum number of fused tiles that won't crash.