cmake: use FindSodium module
cmake: correct find function
Uupdate GSL referenece in packaging script.
Merge pull request #984 from ricnewton/master

Fix windows non-unicode build
Added link to zmq_msg_gets
Problem: zmq_socket_monitor code is dirty

Specifically:

* zmq_event_t should not be used internally in libzmq, it was
  meant to be an outward facing structure.

* In 4.x, zmq_event_t does not correspond to monitor events, so
  I removed the structure entirely.

* man page for zmq_socket_monitor is incomplete and the example
  code was particularly nasty.

* test_monitor.cpp needed rewriting, it was not clean.
Merge pull request #985 from hintjens/master

Cleaned up socket monitor code, tests, and man page
Change OpenEvent to OpenEventW (Windows builds Unicode only).
Merge pull request #986 from evoskuil/master

Windows build/packaging updates.
Added zmq_ctx_shutdown to Makefile

- also removed deprecated man pages from Makefile
- they remain in repository for reference
Fixed NULL security test

Has some bits commented out due to #939, now work.

Note: there is an issue in libzmq when binding/unbinding or
connecting/disconnecting (I did not investigate deeper) the
same socket several times. Even closing the socket with zero
linger, zmq_ctx_term will block. The workaround in this test
case is to close the sockets for each test step.
Added more scaffolding for security

- additional messages to help people debugging security errors
Merge pull request #987 from hintjens/master

Various small cleanups
Add pointer to properties into message structure
Merge pull request #988 from hurtonm/master

Add pointer to properties into message structure
Update function prototype for zmq_msg_gets ()

Added modifiers reflect the following properties:
- zmq_msg_gets () does not mutate property parameter
- zmq_msg_gets () returns a pointer to memory the caller should not
  modify
Merge pull request #991 from hurtonm/master

Update function prototype for zmq_msg_gets ()
Define i_properties interface

- copy and move message operations are updated to maintain proper
  reference count of properties object
- zmq_msg_gets updated to use i_properties interface to fetch property
  value
- setter/getter added to msg_t class
Merge pull request #992 from hurtonm/master

Define i_properties interface
Allow to set up a source address and port for outgoing tcp connections in zmq_connect()

Few examples:
tcp:://192.168.0.4:55555;192.168.0.254:1234
tcp:://192.168.0.4:0;192.168.0.254:1234
tcp:://eth2:55555;192.168.0.254:1234