Extract and modify .bin archives used in the Shiny Festa PSP game

Just thought I would share a draft of an archive manager I created some 2 years ago for the Idolm@ster PSP game.
Basically it allows you to work with game .bin files as archives, currently supporting operations of extracting a file from any depth within the archive and replacing a file from the top-level only.

Nothing to look at yet, I doubt I will continue development given that there's zero demand for this and the game itself got PS3 and iOS releases that people are more interested in.
Still I think I will at least try to format the code better for the potential forkers and perhaps implement the missing "replace at any depth" feature.

TODO: Add archive structure description here, it's surprisingly simple. I wonder how many other games use it. I don't even have a PSP to begin with, I was making this program for a friend.