handle: A Range that handles an Exception

When a Exception occurs inside a range chaining the whole chain dies usually. The Handle range fixes that, as it catches a defined exception and calls an user defined handler on it.
By the way, why make this public. Why not just make it a voldemort type? With all of the template arguments, no one is going to want to do use its name explicitly anyway. I'd say that it should just go inside of `handle` directly as a voldemort type.

Also, with regards to naming, I'd suggest that you use `E` instead of `T` when referring to the exception type. It's not a big deal, but `T` implies more genericity than what's actually going on here. `T` needs to be an exception type.