CODE simplification, call to squirrel class invokes constructor anyway

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6407 8aca7d54-2c30-db11-9de9-000461428c89
const correctness

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6408 8aca7d54-2c30-db11-9de9-000461428c89