LlamaLad7

It would be very nice to have either some form of `onClose` function we could override, or perhaps an annotation we could give to a function, that would allow us...

Add stack checking to old `Target#findInitNodeFor` overload and un-deprecate it.

2

Implements my requested changes from [here](https://github.com/SpongePowered/Mixin/commit/902c3439e8611fa8086e3999e62f3cd64a7b2665#commitcomment-142183895): The only reason MixinExtras uses this method is to match Redirect's behaviour, so I would like it to be kept in line with that....