Fix csharp generator; remove useless type names.
fix generator
move top level let before function
implement VisitNullNode(for String)
support export function, let in function, and cross reference function
after discussion
support full version of CharacterClass
impl VisitAssignNode on CSharpGenerator
start to refactor BunSemanticActionSet..
bug fixed and support \uXXXX in CharacterClass
Merge pull request #96 from imasahiro/FixPegCharacter

Support CharacterClass
Merge pull request #95 from Kouhei-Moriya/SMLSharpGen

support export function, let in function, and cross reference function
Merge pull request #92 from tetsurom/csgen

Fix C# generator; remove unnecessary type name.
change to AllowSkipIndent
Merge pull request #97 from nikuuchi/fix_classic_parser

change to AllowSkipIndent
introducing a superclass of LibBunGamma
introducing TypeCheck for the upper class of LibBunTypeChecker
adding common super class for LetVarNode and FunctionNode
adding apply node2
renaming BunArrayLiteralNode and BunMapLiteralNode
introducing BunTrueNode, BunFalseNode
adding BlockNode