Added a Slicing typeclass.
Got rid of StringShouldWrapper and ResultOfNotWordForString. Merged these
into Any, and just added evidence that T is String. Had to make the Should/MustVerb
traits used by WordSpec, FlatSpec, etc., have an implicit conversion with the same
signature as the one that converts T to AnyShouldWrapper.
Got rid of overloaded aall/every/etc methods that did the String element. Now
it should work with dynamic proxies and should be possible to do the
inspector shorthands generalization noew.
Made Slicing private.
Enhanced Inside to gives multilines indented error messages.
Changed Inside error message indentation to be "inside-out" as suggested by Bill.