renamed Predicate (and Predicate2, AtomicPredicate) within the package
phrase to Verb, etc
renamed ArityPredicate to VerbalPredicate (we don't want to collide
with the Guava Predicate, which also has a different meaning, for it
has a boolean return type);
Introduced the Role and Roles types; a Roles is contained 
in a VerbalPredicate (along with a Verb);
changed interface Preposition by removing the essence() method;
created AtomicPreposition<T> implementing Preposition and removed the 
Basic implementation nested class from Preposition;
created some prepositions in Preposition ("with" and "to")
implemented Role on Preposition;
implemented Roles and Complements with ArrayList
made arity() public, solving multiple bizarre compile errors