A python3 version of ncmdump, which converts netease private music format into regular formats like mp3.

Thanks to anonymous5l/ncmdump who gave the descryption algorithm of .ncm file, and nondanee/ncmdump who provided the structure of python program.

I removed some codes which were intended to provide compatibility between python 2 and 3, and made the code shorter and slightly easier to understand. Especially, an generator is used to build the stream cipher.