Suggestion to add base85 / ascii85 and variant ZeroMQ (Z85)

[misuo]

Few pointers:

• https://en.wikipedia.org/wiki/Ascii85
• https://www.johndcook.com/blog/2019/03/05/base85-encoding/
• https://cryptii.com/pipes/ascii85-encoding

[Kronuz]

Sounds good! I think it should be really simple to add those. Care for a pull request? You should only need to add the alphabets for all the variants here: https://github.com/Kronuz/base-x/blob/master/base_x.hh#L613