Implement local security

[vabold]

Due to this application's reliance on external input, whether that be in the form of supplied ghost files or command line arguments, security is an important concern.

This is an ongoing tracking issue - any security concerns should be mentioned in the comments so I can add them here.

• Replace EGG::Decomp::DecodeSZS with MKW-SP's decoding function
• KMP validation #24

[vabold]

1123988 addresses a vulnerability in EGG::Decomp::DecodeSZS - I'm unclear on whether or not this should close the tracking item.

[malleoz]

I don't think it should close this. We should do a complete audit of all files that can be passed in including rkg, krkg, szs, and the files archived within the szs itself. I assume there are no other vulnerabilities, but we should wait and do a full audit imo