Add busy lockout to remote mode handling.

NXDNControl.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015-2019 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -45,6 +45,8 @@ public:
 
 	void clock(unsigned int ms);
 
+	bool isBusy() const;
+
 private:
 	unsigned int               m_ran;
 	unsigned int               m_id;