Template improvements

* refactors templates/table.html into templates/generic_index.html
* adds DummyFilterInput as do-not-render-widget
* hardens combination of q filter and other filters on index view rendering

intervention/forms.py

@@ -218,3 +218,13 @@ class OpenInterventionForm(EditInterventionForm):
         # Disable all form fields
         for field in self.fields:
             self.disable_form_field(field)
+
+
+class DummyFilterInput(forms.HiddenInput):
+    """ A dummy input widget
+
+    Does not render anything. Can be used to keep filter logic using django_filter without having a pre defined
+    filter widget being rendered to the template.
+
+    """
+    template_name = "intervention/dummy-filter-input.html"