Tokens cleanup

Move methods used only in one fixer from Tokens into that fixer and small fixes/improvements:

* `Tokens::applyAttribs`, `Tokens::grabAttribs*` - move to VisibilityFixer
* `VisibilityFixer::applyAttribs` - create correct whitespace token, no `new Token(' ')` (missing of `T_WHITESPACE`)
* Tokens - use `Token::equals`/`Token::equalsAny` when deal with `{`/`}` or multiple values