FIX: check next tile is recent bridge better

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@7251 8aca7d54-2c30-db11-9de9-000461428c89
CHG: more often use max speed value when on flat straight track

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@7252 8aca7d54-2c30-db11-9de9-000461428c89