Add hook for modloader

[DanielLMcGuire]

Description

This adds a simple hook for modloading systems, including my own

Changes

Added hook for potential modloaders

extern "C" __declspec(dllexport) Minecraft* GetGameInstance();

See https://github.com/DanielLMcGuire/LCE-SDK

[void2012]

Is this exact approach already broadly established in the modding community? Also, I would consider putting a calling convention and extern "C" here.

[DanielLMcGuire]

Usually we would do a ton of math and tests to find the pointer offset ourselves, but this makes my life less hell

Other than that yes

[void2012]

I understand, but we need a calling convention and extern "C" to avoid MSVC artifacts and make this compatible with other compilers

[DanielLMcGuire]

I put one already

[void2012]

Ah, didn't see the extern "C" at the first look, sorry.
As for the calling convention, it appears that we target only x64 now, so we're fine because it's mostly x86 headache