Markov Proc

Created by: Shadowmech88

Adds a markov_chain() proc which takes a string and returns a string containing a generated markov chain using the words in the input string.

I don't know if it could be different or more optimized or what, I just attempted to 1:1 port the first example I found on Google.

I plan to maybe use this in a later feature but I thought it'd be good to add this by itself first.