Library for calculating login hash

[gtker]

https://wowdev.wiki/CMD_AUTH_LOGON_PROOF_Client#Packet_Layout crc_hash field is calculated through the https://wowdev.wiki/CMD_AUTH_LOGON_CHALLENGE_Server#Packet_Layout crc_salt and various file in the game directory. While this is no no way used for anything other than acting as a client, it could be useful to have as a library.

vmangos has a C++ version.