[PD] zero-mq external

[ub at xdv.org]

hello pd-list,

ever dreamed of complex, distributed, networked architectures involving pd?

well, this external might help to reduce the boilerplate patching for
any such plans a lot.
zero-mq [1] is a low-latency, low-level messaging library with a vast
family of language bindings and its own ideology of usage patterns to
reliably solve common distributed computing problems.

the message-parsing code for the external is cloned from
netsend/netreceive so the external is mostly FUDI compliant. mostly,
because it doesn't support binary mode.

this is alpha (at best), so it needs testing. let me know how it goes.
also if you spot something dodgy in the code. long time no C.

cheers,
ub

[1] http://zeromq.org/