EMA

* adds Ema model (basically Compensation inherited)
* adds index view for EMAs
* fixes drop-down link bug for menu 'More' in navbar
* refactors some more forms to use process_request()
* adds modified attribute to BaseResource for easy last_modified check
* adds setting of modified attribute in all places where UserAction.EDITED is added to log
* adds EMA_ACCOUNT_IDENTIFIER_LENGTH and EMA_ACCOUNT_IDENTIFIER_TEMPLATE to ema/settings.py
* adds EmaAdmin to ema/admin.py
* fixes wrong title in intervention detail view html for revocations
* adds support for subtitle variable to BaseTable and generic_index.html
* drops next_version attribute from models
* adds/updates translations
* adds default ordering for UserActionLogEntry
   * removes extra ordering in log modal rendering

compensation/models.py

@@ -91,8 +91,8 @@ class CompensationAction(BaseResource):
 
 class AbstractCompensation(BaseObject):
     """
-    Abstract compensation model which holds basic attributes, shared by subclasses like the regular Compensation
-    or EcoAccount.
+    Abstract compensation model which holds basic attributes, shared by subclasses like the regular Compensation,
+    EMA or EcoAccount.
 
     """
     responsible = models.OneToOneField(
@@ -112,9 +112,6 @@ class AbstractCompensation(BaseObject):
     geometry = models.ForeignKey(Geometry, null=True, blank=True, on_delete=models.SET_NULL)
     documents = models.ManyToManyField("konova.Document", blank=True)
 
-    # Holds a successor for this data
-    next_version = models.ForeignKey("Compensation", null=True, blank=True, on_delete=models.DO_NOTHING)
-
     class Meta:
         abstract = True