- Don't use uuid_compare() as it will get the wrong version of the
  function under FreeBSD which has a uuid library build into libc with
  different function signatures from libuuid but some overlapping names.
- Reorganise the uuid code to limit the used external symbols to uuid_generate(),
  uuid_parse(), uuid_unparse()
- Minimise the framing::Uuid code so that it is a simple wrapper around types::Uuid