Solution: revert the revert!

Revert "Problem: regression in 4.2.3 went unnoticed, want to release 4.2.5"

This reverts commit 5f17e26f.

Problem: regression in 4.2.3 needs to be fixed before 4.3

Solution: note bug fixes

Solution: revert DRAFT -> STABLE API transition so that we can do a
bugfix-only 4.2.5 release.
Will be re-reverted once tagged.

Revert "Problem: ZMQ_BINDTODEVICE has met STABLE conditions"

This reverts commit 3cb79f50.

Revert "Problem: ZMQ_MSG_GSSAPI_* have met STABLE conditions"

This reverts commit 374da420.

Revert "Problem: ZMQ_MSG_T_SIZE has met STABLE conditions"

This reverts commit 6411c4a2.

Revert "Problem: docs say STABLE API still in DRAFT"

This reverts commit 9f2f30b7.

Problem: backward incompatible change to NULL with ZAP

Solution: like for other mechanism, do not enforce strict ZAP protocol
adherence unless the specific socket option is enabled with NULL auth.

Add test to exercise this functionality, and fix ZAP test to set the
socket option when it uses NULL auth.

See: https://github.com/zeromq/pyzmq/pull/1152

Solution: override unused parameter for NULL wrapper

Problem: some inaccuracies in manpages

Solution: fix it, as since 4.2.0 there is no ordering constraint
anymore
Fixes: #2854

Solution: clarify it since it's a common source of confusion

Solution: update them

Fix gcc build problem

Fixed gcc-related build problem resulting from `-errwarn=%all` switch.

Fixes #3012.

Problems: some APIs have met stable conditions

Solution: move them from DRAFT to STABLE since it's been in a public
release, committed for 6+ months and has not changed.

Solution: move them from DRAFT to STABLE since it's been in a public
release, committed for 6+ months and has not changed.

Solution: update manpages

Solution: move it from DRAFT to STABLE since it's been in a public
release, committed for 6+ months and has not changed.
Given a new STABLE symbol has been added, bump minor version number.

Problem: 4.2.4 is out, version is out of date

Solution: bump to 4.2.5

Solution: add it

Migrate test_reqrep_tcp to unity

Solution: replaced by a comment explaining why the calls are in the test

Solution: extracted make_connect_address

Solution: extracted bind_loopback

Solution: migrate to unity

Problem: NEWS out of date

Solution: note new features, APIs and major user-visible bug fixes

Problem: Unnecessary errno_assert

Problem: ZMQ_DISH over UDP triggers errno_assert() after hitting wate…

Problem:  global random init/deinit breaks existing applications

Solution: restrict it only to the original issue #2632, Tweetnacl on
*NIX when using /dev/urandom, ie: without the new Linux getrandom()
syscall.

Existing applications might use atexit to register cleanup functions
(like CZMQ does), and the current change as-is imposes an ordering
that did not exist before - the context MUST be created BEFORE
registering the cleanup with atexit. This is a backward incompatible
change that is reported to cause aborts in some applications.

Although libsodium's documentation says that its initialisation APIs
is not thread-safe, nobody has ever reported an issue with it, so
avoiding the global init/deinit in the libsodium case is the less
risky option we have.

Tweetnacl users on Windows and on Linux with getrandom (glibc 2.25 and
Linux kernel 3.17) are not affected by the original issue.

Fixes #2991

Migrate further tests to unity

Solution: migrate to unity, merge into test_radio_dish, and split up test cases

Solution: migrate to unity

Solution: migrate to unity, and split test cases