The last vestige of the inaccurate 'kilobytes' when we meant 1024 is
now gone.  And virsh is now useful for setting memory in units other
than KiB.

* tools/virsh.c (cmdSetmem, cmdSetmaxmem): Use new helper routine,
allow passing bogus arguments on to hypervisor to test driver
sanity checking, and fix leak on parse error.
(vshMemtuneGetSize): New helper.
(cmdMemtune): Use it.
* tools/virsh.pod (setmem, setmaxmem, memtune): Document this.