Change name 'Multiplex Editor' to 'Transport Editor'

This is more consisstent as a multiplex is called a transport
everywhere else in mythtv-setup.

mythtv/libs/libmythtv/transporteditor.cpp

@@ -182,7 +182,7 @@ void TransportListEditor::SetSourceID(uint _sourceid)
 TransportListEditor::TransportListEditor(uint sourceid) :
     m_videosource(new VideoSourceSelector(sourceid, QString(), false))
 {
-    setLabel(tr("Multiplex Editor"));
+    setLabel(tr("Transport Editor"));
 
     addChild(m_videosource);
     ButtonStandardSetting *newTransport =