Reduces message cloning overhead for single recipients

I think this works for the case where [[msg, msg]] is returned to one output, but when [[msg, msg], msg, msg] is returned the last two are going into the (wires.length == 1) if statement and aren't getting cloned.

So I'm not sure where to get how many wires are ouputted from.

(Also I added a js formatter to Sublime which is why it's reformatted a fair bit of the code just adding spaces in!)