cleanups: removing unused code, simplifying rnTable entries so they
only one push per item instead of an array of pushes
eliminated AcceptActions and PushActions -- accept actions are just
the value true, and push actions are just the state they go to.
removed last vestiges of Lits and string literals in grammar rules
refactoring tokenizer to use a single common implementation
forgot to pass along match into post-processing step
Updating use of sets to remove generic (but convoluted) implementation
of OrderedSet in favor of KeyedSet (where entries have a specific key
field that is their unique identifier in that set), IntSet (a set of
integers) and SetOfSets (that takes a comparison for how to compare
its elements for set equality).  This cleans up the ugliness around
lookup up "itemsByKey" and then asserting that there's exactly 1 such item...
no need to write redundant token values