From now on, I'll delete code from the legacy codebase directory as soon as specific features from it are rewritten... Because it's a mess to navigate.
* Codestyle fixes.
* NCA contexts for NCAs with titlekey crypto will now be generated even if the ticket can't be retrieved, in order to be able to use ncaReadContentFile() with them.
* Moved aes128XtsNintendoCrypt() out of nca.c.
* Updated disclaimer in all source files.
* Improved signed payload (certificate, ticket) handling.
* Prefer strlen + strcmp over strncmp whenever possible.
* Simplify header file inclusions in source files.
* Simplify background gamecard thread logic.
* Properly close keys file handle if there's a key parse error.
* Update NcaKeyGeneration enum.
* Small changes to save.c/h.
Will probably have to revert some USB changes...
