Add mode dependent working frequencies

Working frequencies are mode dependent  and a reset to defaults button
has been added.

Also re-factored much of the model  and item delegate code to simplify
several  of the  model  implementations. Introduced  a single  routine
called from main to register the custom types with Qt.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5453 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

main.cpp

@@ -23,7 +23,7 @@
 #endif
 
 #include "revision_utils.hpp"
-
+#include "MetaDataRegistry.hpp"
 #include "SettingsGroup.hpp"
 #include "TraceFile.hpp"
 #include "mainwindow.h"
@@ -31,6 +31,8 @@
 
 int main(int argc, char *argv[])
 {
+  register_types ();            // make the Qt magic happen
+
   // Multiple instances:
   QSharedMemory mem_jt9;