Add 'virsh event --list' and 'virsh event [dom] --event=name
[--loop] [--timeout]'. Borrows somewhat from event-test.c,
but defaults to a one-shot notification, and takes advantage
of the event loop integration to allow Ctrl-C to interrupt the
wait for an event. For now, this just does lifecycle events.
* tools/virsh.pod (event): Document new command.
* tools/virsh-domain.c (vshDomainEventToString)
(vshDomainEventDetailToString, vshDomEventData)
(vshEventLifecyclePrint, cmdEvent): New struct and functions.
Signed-off-by: Eric Blake <eblake@redhat.com>