massively simplify grammar, in order to allow examples to be much simpler and more focused on the important issues of parser combinators and monad transformers:

 - remove string, number tokens
 - simplify symbol definition

create new simple parser implementation, and describe it in write-up, as simplest version 1 parse tree and recognization demonstration
remove old grammar and parser level 1, as they are too complicated to give a succinct demonstration of.  rename parsers to reflect order
markdown formatting of grammar