Add busy lockout to remote mode handling.

DMRSlot.cpp

@@ -1,5 +1,5 @@
 /*
- *	Copyright (C) 2015,2016,2017,2018 Jonathan Naylor, G4KLX
+ *	Copyright (C) 2015-2019 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
@@ -2091,3 +2091,8 @@ void CDMRSlot::insertSilence(unsigned int count)
 		n = (n + 1U) % 6U;
 	}
 }
+
+bool CDMRSlot::isBusy() const
+{
+	return m_rfState != RS_RF_LISTENING || m_netState != RS_NET_IDLE;
+}