Fix logger emulator to respect debug mode flag
Simplify two-daemon background task to one-daemon

The old two-daemon kludge is suitable when signal processing is not
important.  When we have to wait for both I/O event (local command) and
signal, we'll simply use self-pipe trick, and putting everything in one
single loop.
Revert "Simplify two-daemon background task to one-daemon"

This reverts commit 8e64d9b584f5222fc27b3ab6d9922e3718ed703f.

Revert to the two-daemon approach to avoid possibly nasty wall clock
references.
Make heartbeater restart with approximately correct timeout on interrupt

When the timed poll() is interrupted, the heartbeater will
find a good wall-clock approximation to the remaining time
and restart the poll() with this timeout, maintaining a 60-second
beat rate.
Fix timestamp format in sig-safe logging emulator
Added logging in command listener's Lusering code