Register subject field for group edit form and move form extensions to form_extensions

aleksis/apps/chronos/form_extensions.py

+from django.utils.translation import gettext as _
+
+from material import Fieldset
+
+from aleksis.core.forms import AnnouncementForm, EditGroupForm
+
+AnnouncementForm.add_node_to_layout(Fieldset(_("Options for timetables"), "show_in_timetables"))
+EditGroupForm.add_node_to_layout(Fieldset(_("Optional data for timetables"), "subject_id"))

aleksis/apps/chronos/forms.py

@@ -4,8 +4,6 @@ from django.utils.translation import gettext_lazy as _
 from django_select2.forms import ModelSelect2MultipleWidget
 from material import Fieldset, Layout
 
-from aleksis.core.forms import AnnouncementForm
-
 from .models import AutomaticPlan, LessonSubstitution
 
 
@@ -26,9 +24,6 @@ class LessonSubstitutionForm(forms.ModelForm):
         }
 
 
-AnnouncementForm.add_node_to_layout(Fieldset(_("Options for timetables"), "show_in_timetables"))
-
-
 class AutomaticPlanForm(forms.ModelForm):
     layout = Layout("slug", "name", "number_of_days", "show_header_box")