Add ZMTP link to zmq_tcp doc. 

Include a note with a link to ZMQ RFC 15 for the ZMTP protocol
description.

Fixed doc for SNDHWM

Copy monitor specific event endpoints to event messages as the engine etc. can be released at anytime

This reverts commit 1a18c7b0, reversing
changes made to bef9a41b.

[LIBZMQ-450] Copy the stream engine endpoint - string reference caused memory corruption

Issue 468

XPUB "verbose" mode excludes unsubscriptions

Fix addresses on triggered events

Fixed test compilation issue by using memset/memmove rather than bzero/bcopy

Minor code cleanup

Resolve LIBZMQ-465

Code cleanup

Simplify implementation of DEALER socket

Addded ROUTER-ROUTER (back) as valid combination

Cmake minor version labeling and sync with 3.x

Code cleanup

Fix raw mode on reconnect

Zeromq shall never send/receive socket identifiers for sockets in raw
mode. The existing implementation breaks this requirement after
reconnection.

Add test when the zeromq socket connects to a TCP socket.
The test now fails due to bug in the zeromq library.

session_base: code cleanup

- add unlikely hints
- drop unnecessary assertion
- style fixes

There is no need to require the 'more' flag in the provided message
structure be 0 when pulling message from the session.