apps: Fixing bug with setting Size/MaxSeq in ndn::ConsumerWindow

Before this fix, recently introduced alternative MaxSeq, made parameter
Size essentially useless.
diff --git a/apps/ndn-consumer-window.h b/apps/ndn-consumer-window.h
index 2057123..e89d0a7 100644
--- a/apps/ndn-consumer-window.h
+++ b/apps/ndn-consumer-window.h
@@ -88,6 +88,12 @@
   void
   SetMaxSize (double size);
 
+  uint32_t
+  GetSeqMax () const;
+
+  void
+  SetSeqMax (uint32_t seqMax);
+
 private:
   uint32_t m_payloadSize; // expected payload size
   double   m_maxSize; // max size to request