partial implementation of LL1 Parser
Production now supports __hash__
getProductionsBySide supports single symbols for look up
LL1RecursiveDescentParser: general fixes
moved factory* to Factory
moved checker_factory to Checker module
using check function instead of factory
adds iterable checker
hash support for regexp grammars
IterableChecker exception handling
added some docstrings
removed pika from requirements
fixes in calculator functional test
added missing import
Merge branch 'master' into diff