Leetspeak translating goodie

This is a fairly simple goodie translating the user's request into l33t sp34k (the hard one !).
It triggers on the start/end following keywords : 'leetspeak', 'leet speak', 'l33tsp34k', 'l33t', 'l33t sp34k'.

And I messed up a little bit my commits but I hope it's ok.