FIX:Posix build

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6996 8aca7d54-2c30-db11-9de9-000461428c89
FIX: bridge builder and powerlines

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6997 8aca7d54-2c30-db11-9de9-000461428c89
More informative error messages when loading of themes fails

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6998 8aca7d54-2c30-db11-9de9-000461428c89
FIX: directories of thems search

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6999 8aca7d54-2c30-db11-9de9-000461428c89