Remove PDU counters

These aren't as useful as the Trace facility.

Signed-off-by: Tom Grennan <tom@apptimist.co>
Move the BigEndianUnix epoch time conversion to a wrapper package.

Signed-off-by: Tom Grennan <tom@apptimist.co>
buffer optimization

Receive/open and seal/transmit with pre-allocated buffers.
Also, receive PDU data into struct that morphs from memory
to temporary file buffer as it exceeds page size.

Signed-off-by: Tom Grennan <tom@apptimist.co>
Move the pdu format and parsers under that directory.

Signed-off-by: Tom Grennan <tom@apptimist.co>
replace file and message PDUs with repos

Signed-off-by: Tom Grennan <tom@apptimist.co>
lots of stuf

- add adm and srv pseudo Main that can be called from their
  respective wrappers or used together in tests like
  echo_test
- add keys to generate random keys and output in yaml format
  used by adm and srv configuration
- replace Echo and Trace PDUs with Exec

Signed-off-by: Tom Grennan <tom@apptimist.co>