Merge pull request #343 from Talksum/master

zproxy socket identities
fix for broken identity test in zproxy
Merge pull request #345 from taotetek/master

fix for broken identity test in zproxy
Simplified zproxy

- classic complexity-oriented design! API was trying to provide a socket
  abstraction, except it wasn't an abstraction. The use of methods like
  "set frontend identity" that literally set the frontend identity,
  except via a long and complex wrapper, are a red flag. The abstraction
  should simplify, not complicate. The old API was clearly going to lead
  to endless growth (set frontend HWM, set frontend read timeout...).

- version detection was complex. I added detection for zmq_proxy_steerable
  via configure.ac.

- removed support for pre-V4 versions of libzmq, since the old zmq_proxy
  function needs no async wrapping. If zmq_proxy_steerable isn't present
  the constructor returns NULL.

- capture is moved out of the constructor since it's a minority use case.
Compiler warning/failure on libzmq 3.2
Merge pull request #346 from hintjens/master

Simplified zproxy
Cleaned up zbeacon

- unicast/send methods do not IMO belong in this class -- they are
  nothing to do with beaconing, and are instead a use of classic UDP.
- I've moved some low-level UDP methods into zsys.
- we would better IMO focus on a udp:// transport in libzmq.
- we can recreate the unicast send/recv in zsys if needed, as synchronous
  methods.
Merge pull request #347 from hintjens/master

Cleaned up zbeacon
Added comment to txp socket init, fixes #348
Selfishly added myself to AUTHORS
Merge pull request #349 from ulikoehler/fix348

Added comment to txp socket init, fixes #348
Various small fixes

- zcert had incorrect sodium.h size tests
- czmq_selftest wasn't running zproxy tests
- czmq.h didn't include zmonitor.h
Merge pull request #352 from hintjens/master

Various small fixes