* src/libvirt.c (virDomainMigrate): Added virDomainMigrate
API call.
* src/xend_internal.c, src/xen_unified.c: Support for migration
of Xen domains.
* src/xen_internal.c: Xen capabilities indicates level of
support for migration.
* qemud/remote.c, qemud/remote_protocol.x, src/remote_internal.c:
Support for migration between remote hypervisors.
* src/virsh.c: Added 'virsh migrate' command.
* docs/libvir.html, docs/hvsupport.html: Updated hvsupport
documentation.