origin: Add id property and adapt to changes

The id property will be used to keep track of which origin was used for a call,
so that we can default to reusing the same origin when placing a call from the
history.

src/calls-origin.h

@@ -51,6 +51,7 @@ struct _CallsOriginInterface
 typedef void (*CallsOriginForeachCallFunc) (gpointer param, CallsCall* call, CallsOrigin* origin);
 
 char *                 calls_origin_get_name                (CallsOrigin *self);
+char *                 calls_origin_get_id                  (CallsOrigin *self);
 GList *                calls_origin_get_calls               (CallsOrigin *self);
 void                   calls_origin_foreach_call            (CallsOrigin *self,
                                                              CallsOriginForeachCallFunc callback,