Add the ability to see the color of the differents authors

[yodatak]

Is your feature request related to a problem? Please describe.
I want to know with author is writing and what does is does like if it add a word i want to see the modification

Describe the solution you'd like
An idea of the solution will be to do something like etherpad and add color for etch user or a fancy annimation

by exemple :
https://mensuel.framapad.org/p/Va4yx60jcGawKowNCX37

[juliushaertl]

Duplicate of #91

Let me rename that so it is a bit easier to find.