Fire warning only if necessary

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6308 8aca7d54-2c30-db11-9de9-000461428c89
FIX: when removing powertunnel remove unconnected powerlines at tunnel end

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6309 8aca7d54-2c30-db11-9de9-000461428c89
remove unused methods

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6310 8aca7d54-2c30-db11-9de9-000461428c89
CODE: use ptrhashtable_tpl instead of slist to mark non-ground tiles - should be faster

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6311 8aca7d54-2c30-db11-9de9-000461428c89
CHG: city bridges will be created without owner

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6312 8aca7d54-2c30-db11-9de9-000461428c89
FIX: uninitialized variable werkzeug_t::flags

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6313 8aca7d54-2c30-db11-9de9-000461428c89
forgot to commit this

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6314 8aca7d54-2c30-db11-9de9-000461428c89