Fix windows build and update to QuantLib 1.4

This PR comes with a real solution for the Singleton issue on Windows. It also updates the code to use QuantLib 1.4.

! Builds instructions are not updated yet. This code uses a QuantLib dll that must be built with the symbol.def file attached to this PR and a very small path on ql/settings.hpp (dllexport on the Settings class).

This PR requires testing on Win64 and non-windows platforms