Precompiled header unwinding

It will be more easy to plan new changes into the engine and faster to compile changed parts with CMake generated files while headers are in the standard way.

I will keep fixing these but this is shows that it can be done without breaking anything as I unrolled the integral part, idlib, out from the header pre-compilation.

There is always a possibility that we merge this once complete but the first part should be right here.

Thank you for your great work tr3b!