Update FreeSurround

[tygyh]

Since FreeSurround seems to have been abandoned by its original author, I've decided to start maintaining it on my own to use it with Dolphin.

Most of the changes are refactorings and uses of modern c++. A few out-of-bound readings have also been fixed.

[JosJuice]

I think forking a dependency just for the sake of general cleanup is unnecessary. We also don't have the capacity to review 1800 lines of minor changes.

[tygyh]

I think forking a dependency just for the sake of general cleanup is unnecessary.

This is a continuation of #13169. The issue was external, so I fixed it externally. I can change this PR to not include any commit after the point when the vulnerability was fixed if that would make things easier for you

[JosJuice]

As we previously explained to you, there was no vulnerability in the code you changed in PR #13169. Because of that, PR #13169 is just a minor modernization change, which isn't worth forking a dependency for.

[tygyh]

PR #13169 is just a minor modernization change, which isn't worth forking a dependency for.

I think it is worth maintaining all parts of the codebase, even if it is imported from somewhere else. I've began adding doc comments to a few methods and will continue optimizing slow algorithms in my fork since there is no other active development.

The reason I'm continuing this discussion is because it doesn't matter how much I polish the code if no one uses it and since Dolphin already uses the old code I think it would benefit from using the updated code even though it has mostly just been cleaned up and only have a few performance improvements.