Maintanence release

• Add threading example by Stavros Polymenis
• Minor addition to API documentation
• Remove OCaml version requirement in opam package (strictly not part of this release, but still)

OCaml 4.03 Compatability

This release fixes compilation errors when compiling with 4.03 (and 4.04).
Also the release fixes a generic problem with deallocating resources though finalisers. As a result no resources are automatically released though finalisers. However a warning will be printed to stdout if resources are leaked

The release also includes oasis autogenerated files, removing the dependency on oasis when installing

Compatibility with El Capitan and BSD

The build system now also looks for ZMQ headers and libraries in /usr/local.

Compatability zeromq 4.1

Merge pull request #28 from issuu/zmq-4.1

Compatibility with ZeroMQ 4.1

Bugfixes, especially finalization of contexts

In previous 4.0-x releases, calling ZMQ.Context.terminate would trigger errors like

Unix.Unix_error(Unix.EFAULT, "zmq_ctx_term", "")

when the GC later collected the context. That's fixed in this release -- thanks to @whitequark for patch.

Also fixed overflow bug in get_bytes_option -- thanks to @gdsfh for the patch.

Remove get/set_identity socket-type restrictions

Merge pull request #5 from andrewray/master

Remove get/set_identity socket-type restrictions