Provide a function to extract language file and provide them optionally in the api

[rom1504]

Something like python -c "import minecraft_data.lang as l ; l.extract('1.8.8')" would be put in the README and executed by people who need it.
python-minecraft-data would try to load file in the lang dir, then it would provide the data in an usable form, if the files don't exist, the api would just return null.

Related to PrismarineJS/minecraft-data#17

[rom1504]

see https://github.com/SpockBotMC/SpockBot/blob/80816eab3760962413c8d27f8a24a0b63e8f0112/spockbot/plugins/helpers/chat.py#L59