Fix node gyp build node 10

[basti1302]

The node-gyp build breaks on Node.js 10 with

../netlinkwrapper.cc:58:41: error: no matching member function for call to 'NewInstance'
        args.GetReturnValue().Set(cons->NewInstance(argc, argv));
                                  ~~~~~~^~~~~~~~~~~

This change fixes this, so the module can also be used with the latest Node.js version.

Note that the build in Node.js 8 also emitted a corresponding deprecation warning:

../netlinkwrapper.cc:58:41: warning: 'NewInstance' is deprecated [-Wdeprecated-declarations]
        args.GetReturnValue().Set(cons->NewInstance(argc, argv));
                                        ^
/Users/bastian/.node-gyp/8.11.3/include/node/v8.h:3846:3: note: 'NewInstance' has been explicitly marked deprecated here
  V8_DEPRECATED("Use maybe version",

This warning is now also gone when building with Node 8.

I also added a test case for the TCP client functionality and tested the library for all the Node versions from 4 to 10 (latest patch version for each major version) successfully via rm -rf node_modules && npm install && rm -rf package-lock.json && node-gyp rebuild && npm test, so I'm quite confident that the change in the production code doesn't break the library for older versions.

[basti1302]

I realize it has been a while since you last touched the library. If you are no longer maintaining this, please give me a ping.

[basti1302]

^ this change is the actual fix. Some info around that can be found here: https://stackoverflow.com/questions/45388032/how-to-silence-newinstance-is-deprecated-warning-in-node-gyp-rebuild-what

[JacobFischer]

Great work, I'll review this PR this weekend, and merge it if everything looks 👌.

I was planning on fixing the build for v10 via N-API, but was still wrapping my head around it (there's an old branch here on GitHub with the beginning of my inquiries to fix it). I fully intend to still maintain this repo, I just genuinely thought no one besides my own work used this so I could fix it at my leisure.

Thanks again for this.

[JacobFischer]

Reviewed this today. Excellent work. The module still works with older node versions (I tested on v9), while also now working on v10 as you stated. My own tests all passed with no changes to the TCP communications, and you added mocha test is a much needed improvement!

So, I'm merging this, and then I want to do some house cleaning (such as #5). Then I'll publish these changes as a new minor patch (v1.1.0).

Thanks for the excellent work!

[basti1302]

Thanks for reviewing and merging. If you'd publish a new release that includes this in a somewhat timely fashion, that would be awesome.

[JacobFischer]

Planning to publish it today 😄

[JacobFischer]

@basti1302 V1.1.0 is live now:

https://www.npmjs.com/package/netlinkwrapper/v/1.1.0

Thanks again for your work.