error at where variable is used instead of declared

associate related Token to Node

ADD oct/hex integer constant, integer suffix

ADD comments

ADD cast expression

support declaration as clause-1 for for statement

ADD typedef

read from, write to file

move symbol management related code into symbs.c

UPDATE README

ADD enumerated type

ADD union type

ADD arrow operator (->) for struct member selection by pointer

ADD dot operator for struct member selection

ADD struct declaration