Beginning to bring the zmq receiving into the daqd.

Needed to split the zmq_daq.h file into two portions to avoid name conflicts on channel_t structures.  The daqd does not need (cannot use) the version found in the zmq_daq.h.
So zmq_daq_core.h contains the structures and definitions that the daqd needs to injest streams from the FE computers.
zmq_daq.h includes zmq_daq_core.h.

git-svn-id: https://redoubt.ligo-wa.caltech.edu/svn/advLigoRTS/trunk@4469 6dcd42c9-f523-4c6d-aada-af552506706e