quick frontends (QuickContactList): added isEntityInGroup method

frontends/src/quick_frontend/quick_contact_list.py

@@ -263,6 +263,15 @@ class QuickContactList(QuickWidget):
                 return True
         return False
 
+    def isEntityInGroup(self, entity, group):
+        """Tell if an entity is in a roster group
+
+        @param entity(jid.JID): jid of the entity
+        @param group(unicode): group to check
+        @return (bool): True if the entity is in the group
+        """
+        return entity in self.getGroupData(group, "jids")
+
     def remove(self, entity):
         """remove a contact from the list