vm-install can define a Xen virtual machine, and cause an operating
system to begin installing within that virtual machine.

vm-install can be used in a variety of ways:

* It can be used interactively or non-interactively.

* It can automatically pick reasonable VM defaults for a given type
of operating system.

* It can perform completely non-interactive installs, driven via XML
files and/or command line parameters.

* The supporting Python modules can be 'import'-ed into other
Python programs, to create VMs programmatically.