Solution: fix it

Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).

Solution: Phase I - make precompiled.hpp be first file included in every source file

Solution: rename to ZMQ_MAXRT

This is the option name used on Windows, so easier to use and
remember.

Solution: rename socket option (and variables and files) from usefd
to use_fd.

Solution: rename socket option (and variables and files) from
pre_allocated_fd to usefd.

Solution: parse the value set by the ZMQ_PRE_ALLOCATED_FD sockopt
when creating a new TCP socket and use it if valid.
Add new tests/test_pre_allocated_fd_tcp.cpp unit test.

Solution: update to 2016

LIBZMQ-195 allow explicitly setting sndbuf and rcvbuf to 0 (see https://support.microsoft.com/en-us/kb/201213)

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

- additional messages to help people debugging security errors

This patch allows client applications to retrieve the remote endpoint from a message that originated from a tcp socket

The window scale option carried in SYN segment is computed from socket's
receive buffer size. So we need to set this buffer size before calling
connect or bind.

- we need to switch to PLAIN according to options.mechanism
- we need to catch case when both peers are as-server (or neither is)
- and to use username/password from options, for client

This implements protocol handshake.
We still need to design and implement 1) API changes so a user
can set username and password, and 2) a mechanism for engine
to authenticate users.

Copyrights had become ads for Sustrik's corporate sponsors, going against the original
agreement to share copyrights with the community (that agreement was: one line stating
iMatix copyright + one reference to AUTHORS file). The proliferation of corporate ads
is also unfair to the many individual authors. I've removed ALL corporate title from
the source files so the copyright statements can now be centralized in AUTHORS and
source files can be properly updated on an annual basis.

- Windows CE does not manage security attributes (no SetSecurityDescriptorDacl(), SetEvent (NULL, xxx) ...)
- Windows CE does not inheritance of sockets for child process (SetHandleInformation ((HANDLE) *w_, HANDLE_FLAG_INHERIT...)
- see comments about story "Porting ZeroMQ to Windows Mobile" on webpage http://www.zeromq.org/story:5

This accomplishes the same thing as 2e2ef7fd in a potentially cleaner way.

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

    Handle insufficient resources on accept() decently

    If accept() call fails due to insuffient OS resources
    the new connection is rejected.

Significantly reworked the monitoring infrastructure with a more granular per socket API and to play well with monitoring endpoints in application threads

Compiling without warnings is a good goal, because it makes
new warnings (which probably indicate bugs) stand out rather
than getting lost in the spam.

My fixes fall into two categories:

    - Adding (void) casts of unused parameters, where their
      unusedness seems like a TODO (or in some cases a bug?).

    - Removing parameter names altogether, where the function
      is clearly a stub that will never use its parameters.

Should be no change in behavior.

The endpoint was excluding the tcp://, causing tests to fail

This also fixes a bug in tcp_connecter and tcp_listener, which
generated the event not when they failed to close the socket but
when the succeed to close it.

This reverts commit 029d3dfa.

This reverts commit dde69fb9.

This reverts commit 33459029, reversing
changes made to 889b0e6f.