Fix transparent ground problem ( http://forum.simutrans.com/index.php?topic=10637.msg122955#msg122955 )
Fix transparent ground problem
( http://forum.simutrans.com/index.php?topic=10637.msg122955#msg122955 )

git-svn-id: ad2a872dfb5accdcee22c80d0a136769e8f61d01@1273 e96eaf88-093e-0410-925f-862d53288611

simutrans/pak128,simutrans/pak128,simutrans/pak128,simutrans/pak128,simutrans/pak128