Consider binding void* as number

[donalffons]

Some OCCT functions use void* as arguments or return values, e.g. V3d_View::SetWindow. These cannot be used, since Emscripten complains about void* not being a type for which bindings exist.

As a work-around, we could bind void* as a number (intptr_t in C++ - this should allow 64-bit compatibility) to JavaScript. It should also allow null as an argument. I believe, this would be usable via:

myView.SetWindow(aWindow, null); // pointer value could be passed using someValue.$$.ptr