Problem: proxy_steerable STATISTICS returns conflated buffers

Solution: split each stat into its own frame, to make it simpler and
easier to use it, especially from high level bindings

Problems: proxy stats test break 32bit build, not declared as draft

Solution: ifdef it until it's declared stable

Solution: trucate 64 bit stats in test_proxy, as it's much easier than
to try and print 64 unsigned integers in a portable way

* Issue #2736: Add STATISTICS command to zmq_proxy_steerable()

Variable is assigned but is not used until the end of the function

Excessive check options.mechanism == ZMQ_NULL

The '||' operator is surrounded by opposite expressions. session_base.cpp 377

Problems: compiler warnings

Solution: add /* FALLTHROUGH */ comments so that nagging compilers
don't nag

Solution: wrap arguments with LIBZMQ_UNUSED

Solution: don't pass it

Problem: assertion in src\select.cpp:111 on Windows or hang on zmq_ctx_destroy

Problem: unable to query state of a router for a particular peer

Solution: added function to zmq_draft.h

Solution: added tests

Solution: use inproc transport instead

Solution: refactoring

Solution: modify order of operations, add diagnostic output

Solution: add initial implementation

Solution: added call

Solution: extract as_socket_base_t function

Solution: added test case (with dummy implementation of zmq_socket_get_peer_state)

Solution: extracted test_basic function

Problems: ZMQ_HAVE_O_CLOEXEC not defined by CMake, support for CMake << 3.1 broken

Solution: remove redundant target_sources directive

pending termination while processing an error

Solution: terminate pipe instead

Fixes #2723

Solution: handle case when get_fd_family fails

Solution: add it to CMake's platform.hpp.in

Problem: ZMQ_HAVE_O_CLOEXEC always disabled

Solution: Escape quotes in cmake test.

Problem: Inconsistent size_t/int usage. size_t and int don't match in 64 bit build and produce warnings. Solution: types corrected.

Problem: cosmetic setThreadName() can be fatal

Solution: do not assert() the values returned; if we failed to set the thread name - we just have harder debugging, not flawed production conditions.
Closes github issue #2679
Signed-off-by: Jim Klimov <EvgenyKlimov@eaton.com>

Problem: bug reports are often missing relevant information

Solution: provide template for bug reports

Problem: coverage includes tweetnacl, which is not our code