Added AnyValMatchersSpec that makes sure we can use have length and have size
methods on AnyVals for which the appropriate type classes are available, and
made it work by moving the haveWord should method that requires an Extent
from AnyRefShouldWrapper to AnyShouldWrapper.
Got rid of the last vestiges of dynamic length and size checks, but in the process
I had to (temporarily) ditch support for "x should have (color ("blue"), length (12))" syntax.
Will come back to that later.