Fixes: Polish submit message checking.

Details: Use a global model for nicknames that is shared by all dialogs to solve the updating  problems. Make p4 plugin submit work again. Force a submit prompt in case of shutdown or editor close (as opposed to user clickling on "Submit").

src/plugins/git/gitplugin.h

@@ -171,6 +171,7 @@ private:
     QString                     m_submitRepository;
     QStringList                 m_submitOrigCommitFiles;
     QTemporaryFile              *m_changeTmpFile;
+    bool                        m_submitActionTriggered;
 };
 
 } // namespace Git