[Libwebsockets] proposed API chaneg for external poll fd's, zeromq proxy example

[Michael Haberler]

Hi Andy, 

The API change as discussed, including documentation and adapted test-server.c; this branch also contains the __USE_GNU fix: 

	https://github.com/mhaberler/libwebsockets/commits/change-mode-poll-fd

Ontop of this branch, here is the zeroMQ/libwebsockets proxy, both as a standalone program and a library function:

	https://github.com/mhaberler/libwebsockets/commits/zeromq-proxy-example

I've made an attempt at cmake integration, which I barely know; it works for me so far. See zeromq-proxy/README for usage.

best regards

Michael