FIX: world view position of news window for new monument

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6243 8aca7d54-2c30-db11-9de9-000461428c89
FIX: do not create news window twice; reduce code duplication

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6244 8aca7d54-2c30-db11-9de9-000461428c89