zmq integration, cleaning up

[Magnus Persson]

Im trying to integrate libwkhtmltox with zeromq to ease setting up a cluster of PDF renderers. Im not very well versed with C and my attempts at integrating leads to a pretty segfault on the second iteration :)

Relevant code (client, server and console output) is over at https://gist.github.com/magnusp/ac79f9f986582129f18a.

My question more or less is how to properly clean up after wkhtmltopdf_deinit()? And/or how much can I keep between each run?