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

intervention/templates/intervention/detail/view.html

@@ -94,7 +94,7 @@
                         <th scope="row">{% trans 'Binding on' %}</th>
                         <td class="align-middle">{{intervention.legal.binding_date|default_if_none:""}}</td>
                     </tr>
-                    <tr {% if intervention.legal.revocation %}class="alert alert-danger" title="{% trans 'Missing' %}" {% endif %}>
+                    <tr {% if intervention.legal.revocation %}class="alert alert-danger" title="{% trans 'Exists' %}" {% endif %}>
                         <th scope="row">{% trans 'Revocation' %}</th>
                         <td class="align-middle">{{intervention.legal.revocation.date|naturalday|default_if_none:""}}</td>
                     </tr>