* 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.