Add new encoding: vigenere

[dhondta]

Description

Method of encrypting alphabetic text by using a series of interwoven Caesar ciphers based on the letters of a keyword. Though the 'chiffre indéchiffrable' is easy to understand and implement, for three centuries it resisted all attempts to break it.

Source: Cryptii

Reference

https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher

[dhondta]

Solved with 2586215