easy way to add a group

tiramisu/setting.py

@@ -294,6 +294,9 @@ class GroupModule(_NameSpace):
         """
         pass
 
+    def addgroup(self, name):
+        setattr(groups, name, groups.GroupType(name))
+
 
 class OwnerModule(_NameSpace):
     """emulates a module to manage unique owner names.