Fix printing of file name in template cpp files

pystencils_walberla/templates/Sweep.tmpl.cpp

@@ -13,7 +13,7 @@
 //  You should have received a copy of the GNU General Public License along
 //  with waLBerla (see COPYING.txt). If not, see <http://www.gnu.org/licenses/>.
 //
-//! \\file {{className}}.cpp
+//! \\file {{class_name}}.cpp
 //! \\ingroup lbm
 //! \\author lbmpy
 //======================================================================================================================