Printing is now partial everywhere
Adapted many to work with arbitrary formats
Removed DataFormat data-type

  Added choice combinator
Added more combinators

  Issues:
    - Inchoerent instances for Either
Fixed definition of mkPrinter for Many combinator
Generalized <|> to work with any format
Refactoring

  Code cleaned
  More documentation
Added Char-based formats
Added try in parser for Satisfy

  The proper way would be to use tokenPrim, however our interface
  is too abstract to handle tokens and position.

  try works fine for the moment, but it could turn out to be
  inefficient.