RELICENSE: Robert Gagnon

RELICENSE: Jan Kryl grant

(msys building is buggy, please be aware, it fails to compile on my
machine) also I modified the buildall.bat/buildbase.bat to use correct
MSVC versions instead of "visual studio 2017"

relicensing

Relicense: Alex Grönholm grant

RELICENSE: Andrew Thompson grant

RELICENSE: Andre Caron grant

RELICENSE: Christopher Dolan grant

RELICENSE: Yuval Langer grant

Add relicensing agreement for Elliot Saba

Relicense permission by Paul Colomiets

Fixed path to lib and dll files.

RELICENSE: Added templates for relicensing

RELICENSE: License grant by Roy Lenferink

zmq_curve_keypair(): return result from crypto_box_keypair()

Problem: refactor gone wrong, redundant thread name

Solution: call it simply "ZMQ background" instead of "ZMQ b/g thread"

Solution: fix ifdef check for pthread_setname

Problem: ZMQ background threads are unnamed

Solution: use pthread API to set the name. For now call every thread
"ZMQ b/g thread". Would be nice to number the I/O threads and name
explicitly the reaper thread, but in reality a bit of internal API
churn would be necessary, so perhaps it's not worth it.
This is useful when debugging a process with many threads.

problem:zmq_poll is slow and the API is complicated

solution: deprecate zmq_poll in favor of zmq_poller

problem: zmq_poll is slow because FD is being created on every call

making the creation of FD only when thread safe sockets are in used
within the zmq_poller which improve the zmq_poll performance.

Problem: zmq::signaler_t::send may loop forever

Solution: restore the wsa_assert statement previously removed.