deleted class BoundariesRules
fixed bug of mutable value in function parameters
added any boundaryrule policy
removed unused class BeginSymbol
fixed bug None value for leftpos and rightpos
added missing import
Unknown symbol is a terminal symbol
general refactoring and added unk and null support
new partial grammar list
Merge branch 'master' into unknownsymbol
using None as leftpos and rightpos for NullSymbol
NullSymbol is always false
added check to unknownsymbol
fixed None and Nullsymbol behavior in mixresults and parser
fixed shift for with None position