FIX: vehicles stuck at max speed rather than slowing in corners + restore former precision to calcs

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@7246 8aca7d54-2c30-db11-9de9-000461428c89
FIX: proper background for non-skinned main toolbar

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@7247 8aca7d54-2c30-db11-9de9-000461428c89
FIX: depot allowing selection of line with wrong type

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@7248 8aca7d54-2c30-db11-9de9-000461428c89