In rtrlib.Decode():
* Now check the message length is not greater than a hardcoded limit
(2048) to prevent unbounded memory allocations
* Fix a few unchecked slice accesses that could result in crashes with the
right payload in the PDU_ID_ERROR_REPORT case.
* Add SSH support in library.
* GoRTR and RTRdump to use SSH with user/password or without auth
* Updated README with simple compatilibty matrix,
SSH configuration, Cisco configuration.
