JQuery :: Random Colour On Letters

Basically, I am wrapping a span around each letter of a link element, so i can apply a random class to it - thus creating a rainbow effect on text. My sticking point is that successive letters can't be the same colour, nor can the first letter of successive links.

So 'Link1' wouldn't be acceptable as L and i have the same colour, nor would 'Link1 Link2' as the two L's have the same colour. Also, the code I'm using to append the spans to each letter is also appending a span to any spaces in the links, is there a way I can stop this? I've attached all the files I'm using.

On the example I've attached, I have made each links first letter successive, so the colours will never be the same. I've also made spans from the second letter onwards so they'll never be the same - but occasionally it'll throw up a clash where the first and second letters of each link are the same colour.