[Libguestfs] Proposed new file apis

I've attached a patch to generator.ml for the proposed new file apis. Note that hread, hpread, hwrite and hpwrite are slightly different to the apis I proposed previously. I've also added hallocate for good measure. Matt -- Matthew Booth, RHCA, RHCSS Red Hat Engineering, Virtualisation Team GPG ID: D33C3490 GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490