Fix LIBZMQ-576 - Revert "Merge pull request #510 from miniway/master"

This reverts commit f27eb67e1abb0484c41050e454404cce30647b63, reversing
changes made to a3ae0d4c16c892a4e6c96d626a7c8b7068450336.

Conflicts:
	src/stream_engine.cpp

Conflicts were around additional defaults to the constructor after the
'terminating' default.  The additional defaults were left alone, and
the 'terminating' default was removed.
Adjust NEWS to include LIBZMQ-576
Corrects ypipe initialization when conflate is NOT enabled.  Fixes LIBZMQ-584
Update README.md
Update README.md
Updated NEWS for #584