Avoid loosing messages in the GUI

If the same message was received twice by the msgQ poller before being displayed
by the GUI, one message could ve overwritten.
Now wait for the first message to be consumed before taking the next
one.

asn1_value_editor/gui.py

@@ -117,6 +117,9 @@ class MsgQ_Poller(QThread):
                 time.sleep(0.005)
                 continue
             self.log.debug('MsgQ poller: received message')
+            while (g_tmPool[messageReceivedType].pendingTM):
+                # Wait until possible previous message has been consumed
+                time.sleep(0.005)
             # Copy the message into the ASN.1 type instance of the editor
             g_tmPool[messageReceivedType].asn1Instance.SetData(pDataFromMQ)
             g_tmPool[messageReceivedType].pendingTM = True