Switch to labkit for logging system setup
The only user-visible portions of this are:
- We start supporting the "color" format for logs.
- We now respond to SIGHUP by reopening the log file.
- We now respect the log format when no log filename is specified.
Output to syslog in the event of logging system setup is preserved in OpenSSH mode.
Part of #499 (closed)
Closes #271 (closed)
Edited by Nick Thomas