3.6.0

CHANGES:

• Update README to talk about stdint, not uint (reported by @liyishuai).
  Also, remove out-of-date list of runtime packages needed. The build system can sort that out.

• Remove all inlined attributes (@talex5 #87 #88).
  These cause confusing compiler warnings for users, which can't be disabled automatically,
  and the inlining isn't being used anyway since #83.

• Fix "Unknown interface" error (@talex5 #85).
  It reported the UUID of the actual object, not the UUID that was requested.
  Also, add Registry.pp_interface for better error messages.

• Minor opam fixes (@talex5 #84).
  Depend on dune >= 2.3 and don't try to build benchmarks; that only works on some platforms.

• Bump minimum OCaml version to 4.08.
  4.07 doesn't work due to janestreet/base#94.