Unescape results from PPI::Token::QuoteLike::Words::literal #124

PPI::Token::QuoteLike::Words->literal() was not un-escaping the words, meaning that the caller would get words like "\)" and have to do the unescaping. The method's documentation does not address unescaping, but unescaping seems like the right thing to do.

Lots more test coverage, including nested delimiters and whitespace other than spaces.