CODE: if there is not text to delete then do not calculate key

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6954 8aca7d54-2c30-db11-9de9-000461428c89
CODE: fake tile can be properly destructed now


git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6955 8aca7d54-2c30-db11-9de9-000461428c89
FIX sqapi documentation

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6956 8aca7d54-2c30-db11-9de9-000461428c89
fix comment

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6957 8aca7d54-2c30-db11-9de9-000461428c89
typos

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6958 8aca7d54-2c30-db11-9de9-000461428c89
FIX problems with tunnel building: if building single tunnel mouths tile behind was not properly connected

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6959 8aca7d54-2c30-db11-9de9-000461428c89
FIX: enable tunnel building from tunnel mouth if the tunnel's way has ribi==0

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6960 8aca7d54-2c30-db11-9de9-000461428c89