theme loader added

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6704 8aca7d54-2c30-db11-9de9-000461428c89
removed extra themeseletor_t::

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6705 8aca7d54-2c30-db11-9de9-000461428c89
FIX: add themeselector.cc to makefile

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6706 8aca7d54-2c30-db11-9de9-000461428c89