Move some external files to external/ folder (#744)

It is lot easier to work with automatic formatters if we have external
files in different folder. For some tools we can example just exclude
external all together.

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

ports/bdk-atxx4-mstp/external/avrosp/CommChannel.cpp

@@ -0,0 +1,38 @@
+/*****************************************************************************
+ *
+ * Atmel Corporation
+ *
+ * File              : CommChannel.cpp
+ * Compiler          : Dev-C++ 4.9.8.0 - http://bloodshed.net/dev/
+ * Revision          : $Revision: 1163 $
+ * Date              : $Date: 2006-08-02 15:38:16 +0200 (on, 02 aug 2006) $
+ * Updated by        : $Author: ohlia $
+ *
+ * Support mail      : avr@atmel.com
+ *
+ * Target platform   : Win32
+ *
+ * AppNote           : AVR911 - AVR Open-source Programmer
+ *
+ * Description       : An abstract class for general byte-by-byte communication.
+ *                     Serialport, USB, TCP/IP or similar implementations can be derived
+ *                     from this class to create a technology-independent
+ *                     communication interface.
+ *
+ *                     This abstract class does not provide any constructor as it is
+ *                     too specific for this generalized class. Derived classes should
+ *                     implement their own constructors for specific communication devices.
+ *
+ * 
+ ****************************************************************************/
+#include "CommChannel.hpp"
+
+
+/* Destructor */
+CommChannel::~CommChannel()
+{
+	/* no code here */
+}
+
+/* end of file */
+