Error logging wasn't really correct.
Merge pull request #8 from ArduSat/correct-error-logging

Correct error logging
Make external monitoring possible.
Moved csp_conn.h to the global include directory.
Merge pull request #9 from ArduSat/make-monitoring-possible

Make external monitoring possible.
Added a global flag set when transmission of kiss frames is happening.
Made the variable volatile.
Merge pull request #10 from ArduSat/kiss-hack

Added a global flag set when transmission of kiss frames are happening.
support for up to 2 KISS interfaces on the same node:

* use handles to identify a specific kiss interface
* use handle-specific rx/tx callbacks for plugging into USART drivers
* csp_if_kiss was removed in favor of csp_kiss_get_if(handle)