Solution: Move the macros to a private header.

Solution: Convert to spaces and remove trailing whitespace in these files.

Previously, AddressSanitizer flagged leaks when running
tests/test_many_sockets.cpp.

Of course people still "can" distributed the sources under the
LGPLv3. However we provide COPYING.LESSER with additional grants.

Solution: specify these grants in the header of each source file.

Solution: update for 2015

Fixes #1320

Revert "linking fd to pipe identity via socket option"

This reverts commit fe3e8c5c.

Conflicts:
	include/zmq.h
	src/pipe.hpp
	src/session_base.cpp

Solution: set defaults back to infinity, and add new context
option, ZMQ_BLOCKY that the user can set to false to get a
less surprising behavior on context termination. Eg.

    zmq_ctx_set (ctx, ZMQ_BLOCKY, false);

Solution: set errno to EINVAL when tcp:// endpoint is invalid (was just
leaving errno to previous value).

Since https://github.com/zeromq/libzmq/commit/350a1a, TCP addresses
get resolved asynchronously, so zmq_connect no longer returned an
error on incorrect addresses.

This is troublesome since we rely on some error checking to catch
blatant errors.

Solution add some upfront syntax checking that catches at least the
obvious kinds of errors (invalid characters, wrong or missing port
number).

- limit visibility of pending_connection_t
- add const qualifiers

- add const modifier to address parameter of event generating functions

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.

This reverts commit 79b81f48.
Was causing:

Assertion failed: destroyed (socket_base.cpp:154)
/bin/bash: line 5: 31344 Aborted                 ${dir}$tst
FAIL: test_many_sockets

On TravisCI.