remove useless type hints, make <,>,<=,>= actually return a boolean on the 1-arg arity, as per docstring

The boolean type-hint was useless since clojure only allows long/double primitive type hints, and was also in the wrong position for the same reason of https://github.com/clojurewerkz/scrypt/pull/1

The comparator functions returned the element in the 1-arity version while the docstring explicitely stated that they would return a boolean, fixed the function behaviour.