Solving some deadlocks and crashes

It is still some mystery with two clients and delays
diff --git a/model/sync-logic.h b/model/sync-logic.h
index b5a4174..871ee33 100644
--- a/model/sync-logic.h
+++ b/model/sync-logic.h
@@ -104,7 +104,10 @@
   sendSyncInterest ();
 
   void 
-  processPendingSyncInterests(DiffStatePtr &diff);
+  processPendingSyncInterests (DiffStatePtr diff);
+
+  void
+  satisfyPendingSyncInterests (DiffStatePtr diff);
 
 private:
   FullState m_state;