FIX: update station status bar on screen only when changed

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6473 8aca7d54-2c30-db11-9de9-000461428c89
FIX: force screen dirty when ending fastforward simple drawing mode

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6474 8aca7d54-2c30-db11-9de9-000461428c89