Factor out the runtime

* The runtime previously written by the pywriter is now factored out
  as package
* decoding of input files has been transferred from the Lexer to the
  new InputBuffer abstraction
* Several API changes:
  - Lexer.nextCond -> Lexer.next_cond
  - new InputBuffer API
  - Parser.Parser -> Parser.parse
  - Lexer.lexAll -> Lexer.lex_all
Fix Singleton metaclass
Adapt tests to previous refactoring
Expand Constructor of PySuite for the tests
Improvement: Error message in regex.py
Push through the use of AlphabetStrategies

* This is an important preliminary for unicode support
Add the option section to the parser file, no semantic or syntax yet
test updates