Remove a Unix dependency that snuck into the `Dns_resolver` portable
core, by adding a timeout argument to the `commfn` type.
regenerate oasis
Improve ocamldoc in Lwt_resolver_unix
XMETARequires to avoid runtime dependency on camlp4
add DS to string conversion function
convert a partial match on RR class into a proper failure if it happens
Ensure that all `Dns.Buf.t` buffers are page-aligned, via `Io_page`.

This fixes the DNS library under Mirage/Xen, which zero copies the
Dns.Buf.t and requires this invariant.
travis: +io-page
travis: +sexplib
Merge pull request #14 from avsm/mirage-fixes

Mirage fixes