Fix pgpool.init's long-standing bug of stop/restart failure

In previous, pgpool.init uses killproc for stopping pgpool, but there are
several problems; (1) some child processes can be left since the parent
process restarts killed processes; (2) when pgpool has connection from
clients, pgpool can't stop until connection closed; (3) restart() fails
for these reasons.

In the new version, "pgpool -m fast stop" is used in stop(). The problems
above are resolved and restart() also works well, even when watchdog enabled.
In addition, exit code according with LSB is considered, try-restart
option is implemented, and the old switch option is removed.

Original patch contributed by Ryan DeShone and modified by Yugo Nagata.

See [pgpool-hackers: 239][pgpool-hackers: 512].
Fix pgpool.init's long-standing bug of stop/restart failure

In previous, pgpool.init uses killproc for stopping pgpool, but there are
several problems; (1) some child processes can be left since the parent
process restarts killed processes; (2) when pgpool has connection from
clients, pgpool can't stop until connection closed; (3) restart() fails
for these reasons.

In the new version, "pgpool -m fast stop" is used in stop(). The problems
above are resolved and restart() also works well, even when watchdog enabled.
In addition, exit code according with LSB is considered, try-restart
option is implemented, and the old switch option is removed.

Original patch contributed by Ryan DeShone and modified by Yugo Nagata.

See [pgpool-hackers: 239][pgpool-hackers: 512].