This patch adds a new command "desc" to show and modify titles and
description for the domains using the new API.
This patch also adds a new flag for the "list" command to show titles in
the domain list, to allow easy identification of VMs by storing a short
description.
Example:
virsh # list --title
Id Name State Title
-----------------------------------------------
0 Domain-0 running Mailserver 1
2 fedora paused
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