Payments add modal form

* adds modal form for adding payments
* generalizes generic_table_form.html for table-form-like usage in modal_form.html
* adds css enhancements for focused input fields
* adds BaseModalForm as specification to BaseForm, which inherits the BSModalForm class as well
* adds translations

compensation/urls.py

@@ -19,7 +19,7 @@ urlpatterns = [
     path('<id>/remove', remove_view, name='remove'),
 
     # Payment
-    path('pay/new', new_view, name='pay-new'),
+    path('pay/<intervention_id>/new', new_payment_view, name='pay-new'),
     path('pay/<id>', open_view, name='pay-open'),
     path('pay/<id>/edit', edit_view, name='pay-edit'),
     path('pay/<id>/remove', remove_view, name='pay-remove'),