Debug mode for setting limit of printing token from one lexer.

[daeisbae]

This will prevent infinite loop printing. During lexing, if the lex counting goes wrong it will give result like this.

>>> ! 
...
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!' )
Token( TokenType: Operator Value: '!^C

To prevent the infinite loop of token printing from happening, this implementation is requested