qdev-monitor: Group "device_add help" and "info qdm" by category

qdev-monitor: Group "device_add help" and "info qdm" by category

Output is a long, unsorted list.  Not very helpful.  Print one list
per device category instead, with a header line identifying the
category, plus a list of uncategorized devices.  Print each list in
case-insenitive alphabetical order.

Devices with multiple categories are listed multiple times.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel.a@redhat.com>
Message-id: 1381410021-1538-3-git-send-email-armbru@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>