Its feature already exists in mcmmo plugin, so maybe make this togglable for those who use mcmmo

Oh, I haven't had that enabled before with McMMO, is that a new feature? But thanks a lot - will definitely need a toggle for it then - since a lot of people use McMMO (but also I don't want to rely on "use x plugin if you'd want this feature".

Lifesteal is effectively disabled when setting lifesteal to 0.