Add support for AES-IGE

[watzon]

IGE (Infinite Garbled Extension) isn't very well used in the crypto world, but it does exist. Telegram actually is the only service I know of that makes use of it, and that's exactly what I need it for. In theory, IGE should be fairly simple to implement. I'm attempting it right now, but I am pretty terrible with cryptography.

Some implementations: https://github.com/pyrogram/tgcrypto/blob/master/tgcrypto/ige256.c https://github.com/LonamiWebs/Telethon/blob/master/telethon/crypto/aes.py