Update selectform.py (#173)

Tweak improvement for handling the translation on "form_type" string.

As most event types are already loaded from gramps translation domain, 
we could use existing translations for displaying the localized 'form_type' string.

This minor translation issue is visible when we select a form from the list : the model ignores
the top level string (event type as parent). e.g., "census" instead of "recensement" under the french locale.

Author: romjerome

Form/selectform.py

@@ -110,11 +110,11 @@ def _populate_model(self):
             form_id = get_form_id(source)
             if form_id in get_form_ids():
                 form_type = get_form_type(form_id)
-                if form_type in form_types:
-                    parent = form_types[form_type]
+                if _(form_type) in form_types:
+                    parent = form_types[_(form_type)]
                 else:
-                    parent = self.model.append(None, (None, form_type))
-                    form_types[form_type] = parent
+                    parent = self.model.append(None, (None, _(form_type)))
+                    form_types[_(form_type)] = parent
                 self.model.append(parent, (source.handle, source.title))
         self.model.set_sort_column_id(1, Gtk.SortType.ASCENDING)
         self.tree.expand_all()