#36 Quality checks

* adds AbstractQualityChecker as base for all quality checker instances
* adds InterventionQualityChecker, inheriting from AbstractQualityChecker
* adds functionality to InterventionQualityChecker
* adds/updates translations

intervention/forms/modalForms.py

@@ -208,13 +208,13 @@ class RunCheckModalForm(BaseModalForm):
         """
         super_result = super().is_valid()
         # Perform check
-        msgs = self.instance.quality_check()
-        for msg in msgs:
+        checker = self.instance.quality_check()
+        for msg in checker.messages:
             self.add_error(
                 "checked_intervention",
                 msg
             )
-        return super_result and (len(msgs) == 0)
+        return super_result and checker.valid
 
     def save(self):
         """ Saving logic