v3.2.0

Backwards-incompatible changes

• The capnp opam package no longer depends on the C++ compiler (#47).
  If your project compiles schema files, you should add
  "conf-capnproto" {build} to your opam dependencies.

Other changes

• Add support for OCaml 4.06 (#45).

• Update for API changes in Base and Core_kernel (#44).