lei: support for -$DIGIT and -$SIG CLI switches

lei: support for -$DIGIT and -$SIG CLI switches

I'm a bit spoiled by using single-dash digit options
from common tools: ("git log -$DIGIT", "kill -9",
"tail -1", ...), so we'll support it for limiting
query results.

But first, make it easier to send arbitrary signals to
the daemon via "daemon-kill".  "daemon-stop" is redundant,
now, and removed, since the default for "daemon-kill" is
SIGTERM to match kill(1) behavior.