Replace stack code with IMaterial

[yogwoggf]

Fixes #70

PR Type (tick all that are applicable)

• [ ] Bug Fix
• [x] New Feature (doesn't break Module <-> Lua compatibility)
• [ ] New Feature (breaks Module <-> Lua compatibility)
• [ ] Documentation Update Required

Tested Targets (only applicable for changes to the binary module, delete otherwise)

• [x] windows-x64-release
• [ ] windows-x86-release

Checklist

• [x] I have read and understand the contributing guidelines
• [x] I have tested all aspects of this PR (not required)
• [ ] I have added the watermark on the branding branch with my desired name to any content attached where applicable (only applies to showcase submissions)

Description Before this commit, the AccelStruct would take material information from Lua. Now, it takes information directly from source. Theoretically this should make it faster (I feel it's faster), but I've done no benchmarks yet.

There are definitely stylistic issues with the PR and some design choices that need to be reconsidered, so please review carefully. Also: This can be disabled, so let me know if it should be.

[Derpius]

Either disable those warnings or use a function that checks if a key exists first