Ref T190, text messages can be appended

(same sender sends one message in multiple parts)

src/blackmisc/network/textmessagelist.h

@@ -88,6 +88,8 @@ namespace BlackMisc
             //! Mark all messages as sent
             void markAsSent();
 
+            //! Add a text message, but append it to an existing message if possible
+            void addConsolidatedTextMessage(const CTextMessage &message);
         };
     } //namespace
 } // namespace