Yet another at3+ encoder/decoder

[gid15]

Thanks to serio.
It's inside the PGD file of Fate/Extra CCC (NPJH50505)
If you have the ISO file, use JPCSP or other tools to decrypt the PGD then unpack the cpk, namely the decrypted PGD file, and you should find "at3tool.exe" under the sound/bgm/decode/ folder.

Could you test r3075 and place at3tool.exe under lib/windows-x86 or lib/windows-amd64? I've added basic support for this tool, but could not test it.