move roles, interactions, and private_interactions to attr_reader
squash attr_readers
prefer instance variables

Classes may still used instance variables but the variables are scoped to that
individual class. When using class variables with the @@ prefix, subclasses
may alter that variable for the entire subclass/superclass tree.

This change prevents accidental changes from subclasses of any core class
update generated/Tokens.rb for ivar vs. class-var changes
Merge pull request #8 from saturnflyer/dry-up

Alteration to variable scoping and minor changes to accessor methods