Investigate fastcall as possible replacement for node-ffi

[kleisauke]

I came across fastcall, I thought let's open an issue to track this.

There is a a popular dynamic binding library for Node.js:
node-ffi. Then why we need another one could ask? For performance! There is a good 20x-40x
function call performance overhead when using node-ffi compared to hand made C++ native module, which is unacceptable in most cases (see the benchmarks).

fastcall has an almost 100% node-ffi compatible interface, so it could work as a drop-in replacement of node-ffi.

(I can't work on this before February 2019, since I'm currently busy with my internship.)

[jcupitt]

That looks very interesting!

Yes, let's leave this as an enhancement for Feb.