Minor cleanup and documentation improvements.•••- Only show a generic failure message to the user upon oper failure
due to not having a secure connection or matching cert. fingerprint.
- Update the comment about oper:fingerprint as it can be a space
separated list of fingerprints and not just one.
- Improve a few code comments and formatting.
Remove the original line parameter of On{Pre,Post}Command.•••In the brave new world of message tags and alternate wire formats
this is no longer something that is appropriate to expose.
In reality it was only ever used by m_alias which now reconstitutes
the command name and parameters into a RFC 1459-style message for
whatever it needs to do.