ZeroMQ 3.x Input Plugin

Building this plugin:
Requires libzmq and libczmq.  First, install libzmq from the HEAD on github:
http://github.com/zeromq/libzmq.  You can clone the repository, build, then
install it.  The directions for doing so are there in the readme.  Then, do
the same for libczmq: http://github.com/zeromq/czmq.  At some point, the 3.1
version of libzmq will be released, and a supporting version of libczmq.  
At that time, you could simply download and install the tarballs instead of
using git to clone the repositories.  Those tarballs (when available) can 
be found at http://download.zeromq.org.  As of this writing (5/31/2012), the 
most recent version of czmq (1.1.0) and libzmq (3.1.0-beta) will not compile
properly.  

Imzmq3 allows you to push data into rsyslog from a zeromq socket.  The example
below binds a SUB socket to port 7172, and then any messages with the topic
"foo" will be pushed into rsyslog.

Example Rsyslog.conf snippet:
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$InputZmq3ServerRun action=BIND,type=SUB,description=tcp://*:7172,subscribe=foo

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