Modern build fixes and buffer overrun fixes

[dpw13]

This PR updates mp3splt to build with modern versions of gcc and fixes a number of buffer overrun vulnerabilities. It also introduces clang-format for standardizing the formatting for code across the repo, which will hopefully reduce the number of style changes present in future PRs.

This PR is more informational than an earnest request to merge, as I'm adding some functionality to mp3splt and want to ensure my changes are visible in some way from the original repo. However if anyone is interested in merging and has concerns, I will be happy to address them to maintain a single repo.