Use more Effective C++ code style in Token class:

1)The non-const version of Token::tokAt and Token::linkAt now will use a combination of const_cast and static_cast to remove duplicate code.
2)The non-const versions of Token::find(simple)match are added, in order to avoid the usage of const_cast outside the Token code.
3)As a consequence of 2), an useless const_cast applied to a call of Token::findsimplematch in Tokenizer code is removed.