TODO

- User extendable pattern languages. Thinking of defining all operators
  for all of the types, where the types are computed through a template,
  and then specializing that template to give the desired functionality,
  where the default instantiation results in a failed assertion or some
  such.

- Generic translator, e.g. Translator<CFG, terminal_type, PDA, symbol_type>
  to ease the process of going from symbols in one object to symbols of
  another object. Also allow Translator<CFG, terminal_type> where the source
  and destinations are the same but the objects are different.

- Fix the bug in find_string where n-1 quotations followed by n quotations
  for an n-quotation-delimited string works. This might require changes
  in how UTF8FileBuffer handles unread().

- Make it so that when --stdin is specified, the input is read into memory
  first. This would require changing UTF8FileBuffer, making it more generic
  so that it works on non-files. Right now two passes are needed over most
  things, which means *NIX pipes are out of the question.

- Make input mmap files, and read stdin into memory, possibly using a similar
  mechanism to the buffered text in the ContPEG project. Then allow one to
  use pointer arithmetic to iterate over the bytes of a file.

- Add an option to cfg-parse to split characters by whitespace or some
  other delimiter.

- More thought is needed in the Alphabet trait type, especially with regards
  to serializing and unserializing aggregate objects whose contained objects
  serialize to forms that would require quotation marks. Right now, such
  concerns are completely ignored as I don't have the need to aggregate types
  yet but it would be an immediate issue for the terminals of a CFG, for
  example.