Book again assests correctly

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6533 8aca7d54-2c30-db11-9de9-000461428c89
FIX: comboboxes displaying again current selection

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6534 8aca7d54-2c30-db11-9de9-000461428c89