DESERT / ISRAEL2 ground environment update

DESERT / ISRAEL 2 ground environment update ("tree mod")

Should work with any maps using default SFP1/SFG desert tileset in jet titles from the series. In all cases you'll have to use the desert.cat or manually extract and move the tiles from desert.cat to your terrain folder.

Not tested with the "desert replacement tileset"! Should work, but objects placement will be slightly incorrect.