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.
You should probably add

    See_Also:
         $(LREF thrownIf)

here and one that refers to `handle` in `thrownIf`, since there _are_ some similarities in what they do. I don't think that they should actually be combined though. They're similar but not _that_ similar.