Initial import of gr-zmqblocks OOT project as-is, prior to rework for in-tree
zeromq: initial surgery to add to master build
zeromq: Initial conversion of include/gnuradio/zeromq files
zeromq: first cut at compiling lib/ directory
zeromq: cleanup and reformatting
zeromq: converted SWIG to in-tree build
zeromq: first try at enabling Python.  Segfaults in SWIG code.
Fix ZeroMQ cmake module.
Fix callback function to work with multiple arguments and return None
in case of error.