[Feature] Package Export/Import (#116)

Fixes #90
Fixes #91
Fixes #115
Fixes #104

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#116

epdb/models.py

@@ -578,32 +578,38 @@ class Package(EnviPathModel):
     license = models.ForeignKey('epdb.License', on_delete=models.SET_NULL, blank=True, null=True,
                                 verbose_name='License')
 
+    def delete(self, *args, **kwargs):
+        # explicitly handle related Rules
+        for r in self.rules.all():
+            r.delete()
+        super().delete(*args, **kwargs)
+
     def __str__(self):
         return f"{self.name} (pk={self.pk})"
 
     @property
     def compounds(self):
-        return Compound.objects.filter(package=self)
+        return self.compound_set.all()
 
     @property
     def rules(self):
-        return Rule.objects.filter(package=self)
+        return self.rule_set.all()
 
     @property
     def reactions(self):
-        return Reaction.objects.filter(package=self)
+        return self.reaction_set.all()
 
     @property
     def pathways(self) -> 'Pathway':
-        return Pathway.objects.filter(package=self)
+        return self.pathway_set.all()
 
     @property
     def scenarios(self):
-        return Scenario.objects.filter(package=self)
+        return self.scenario_set.all()
 
     @property
     def models(self):
-        return EPModel.objects.filter(package=self)
+        return self.epmodel_set.all()
 
     def _url(self):
         return '{}/package/{}'.format(s.SERVER_URL, self.uuid)
@@ -911,7 +917,6 @@ class CompoundStructure(EnviPathModel, AliasMixin, ScenarioMixin, ChemicalIdenti
 class Rule(PolymorphicModel, EnviPathModel, AliasMixin, ScenarioMixin):
     package = models.ForeignKey('epdb.Package', verbose_name='Package', on_delete=models.CASCADE, db_index=True)
 
-    # I think this only affects Django Admin which we are barely using
     # # https://github.com/django-polymorphic/django-polymorphic/issues/229
     # _non_polymorphic = models.Manager()
     #
@@ -1128,6 +1133,7 @@ class ParallelRule(Rule):
         return res
 
 
+
 class SequentialRule(Rule):
     simple_rules = models.ManyToManyField('epdb.SimpleRule', verbose_name='Simple rules',
                                           through='SequentialRuleOrdering')
@@ -1959,7 +1965,7 @@ class RuleBasedRelativeReasoning(PackageBasedModel):
         rbrr.package = package
 
         if name is None or name.strip() == '':
-            name = f"MLRelativeReasoning {RuleBasedRelativeReasoning.objects.filter(package=package).count() + 1}"
+            name = f"RuleBasedRelativeReasoning {RuleBasedRelativeReasoning.objects.filter(package=package).count() + 1}"
 
         rbrr.name = name