added some PEG tests
added grammar_factory
Merge branch 'master' into peg
fixes WeightedParser test errors
improved README
Merge branch 'master' into peg
added test for Choice
adds comment
removed Choice as is equivalent to AlphabetListDefinition
improved documentation #57
fixed broken tests
Merge branch 'master' into peg
Alphabets are now GrammarDefinitions
removed Definition from GrammarDefiniton and AlphabetDefinition
fixed Alphabet minsize property
removed unnecessary typechecking
removed USAGE header
Merge branch 'master' into peg
renamed GrammarDefinitoin -> Grammar
added Sequence Checker