plugin events: store interest_id in data:

ID of the item in list of interest is needed to correctly modify (and notably retract) an
event.

sat/plugins/plugin_exp_events.py

@@ -428,6 +428,7 @@ class Events(object):
                 )
             else:
                 timestamp, data = self._parseEventElt(event_elt)
+                data["interest_id"] = item["id"]
                 events.append((timestamp, data))
         defer.returnValue(events)