problem: dynamic cast is causing issue when compiling for nodejs

Problem:  Windows build script requires edit for DevStudio version

Solution: Use CMD.EXE environment variable to extract DevStudio version
number and build using it. This even supports machines with multiple
DevStudio versions installed, as long as the build for each version is
done on a separate window with the correct environment.
If multiple version builds are desired from a single CMD.EXE, edit the
buildall.bat file to uncomment the build statements for each specific
version desired.

Number of fixes for gyp builds

Solution: remove it

libzmq used to switch off pedantic checks when using tweetnacl. As
this is now the default, that means pedantic checks are always off.
This is not good.

Solution: in tweetnacl.c alone, use a GCC pragma to disable sign
comparison warnings. We could also clean the code up yet this is
simpler. In other code, we still want those warnings, hence I've
used a pragma rather than global compile option.

Second, use -Wno-long-long all the time, as this warning does not
work with a pragma.

I removed code that set -wno-long-long, for MinGW and Solaris.

Related problem 2: --with-relaxed is badly named

This option switches off pedantic checks, so should be called
--disable-pedantic. 'with' is for optional packages.

Solution: override in project.gyp, for Linux and OS/X.

Gyp needs its own platform.hpp; there is no way to delete this
file automatically.

Solution: copy gyp's platform.hpp into src, so that things build
properly no matter what the starting state. If you build with gyp
and then try to build using autotools' makefile, you'll get an
error from the platform.hpp.

Solution: add .gitignore in builds/gyp

Solution: raise to 16K

Solution: fix in CMakeLists.txt (already fixed in builds/msvc)

Problem: curve keys getsockopt uninitialised read

Solution: always initialised zmq::options_t class variables arrays to
avoid reading uninitialised data when CURVE is not yet configured and
a getsockopt ZMQ_CURVE_{SERVER | PUBLIC | SECRET]KEY is issued.

Various test fixes

Solution: increase SETTLE_TIME from 50ms to 300ms to avoid failing on
slower environments like through Valgrind on slow VMs.

Solution: suggest to use the common approach of msleep (SETTLE_TIME)
after a connect if necessary, rather than reimplementing a different
way.

Solution: include pthread.h in testutil.hpp, removed from
test_shutdown_stress_tipc in an earlier commit

Solution: rename from test_socketopt_hwm to test_sockopt_hwm in
.gitignore too

Solution: add msleep (SETTLE_TIME) to test_immediate, test_spec_rep
and test_spec_router after the sockets are created and connected to
avoid failing when running in slower environment like through
Valgrind in underpowered VMs.

Solution: use msleep (SETTLE_TIME) everywhere when waiting for the
connections/sockets to be settled instead of a variety of patterns
and functions to make tests more coherent.

Solution: memset temporary buffer before use to reduce Valgrind noise

Solution: memset temporary buffer before use to reduce Valgrind noise

Solution: close socket and destroy context to reduce Valgrind noise

Solution: memset temporary buffer before use to reduce Valgrind noise

Solution: free addrinfo to reduce Valgrind noise

Solution: close socket and destroy context to reduce Valgrind noise

Solution: pass correct size to memcmp to avoid reading uninitialised
areas of the buffer.

Solution: close socket and destroy context to reduce Valgrind noise

Problem: too many CI builds

Solution: remove libsodium and no curve builds from cmake and android

Problem: tests don't build on Windows

There were numerous small issues with test cases:

- some lacked the right source file header
- some were not portable at all
- some were using internal libzmq APIs (headers)

Solution: fixed and cleaned up.

Cleaning up Windows build for gyp

There were numerous small issues with test cases:

- some lacked the right source file header
- some were not portable at all
- some were using internal libzmq APIs (headers)

Solution: fixed and cleaned up.

Solution: document the minimum rules in README.md

Solution: offer a build.bat to help the user.

Making gyp builds work

Solution: it's a lot of work to define the tests in project.gyp
so I did this using gsl to generate the JSON, from a small XML
list of the test cases.

To keep this, and the hundreds of .mk files, away from the root
directory, I've moved the gyp files into builds/gyp, where you
would run them.

It all seems to work now. Next up, OS/X and Windows :)

Doesn't affect building, just potentially confusing.

Solution: fix it.