CODE: Translate and document simworld.h and related files.

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6318 8aca7d54-2c30-db11-9de9-000461428c89
CODE: Minor doc fixes

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6319 8aca7d54-2c30-db11-9de9-000461428c89