remove unused const, document others

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6754 8aca7d54-2c30-db11-9de9-000461428c89
make compiler happy

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6755 8aca7d54-2c30-db11-9de9-000461428c89
sqapi: minor changes

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6756 8aca7d54-2c30-db11-9de9-000461428c89
sqapi: export way system type constants

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6757 8aca7d54-2c30-db11-9de9-000461428c89
sqapi: reworked exporting of year-month integers

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6758 8aca7d54-2c30-db11-9de9-000461428c89
sqapi: fix way_system_types and docs

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6759 8aca7d54-2c30-db11-9de9-000461428c89