Better parsing

[crufter]

I've committed the sin of parsing the selectors with regexps... I will find something like Haskell's Parsec and fix it. The haskell port of this library (https://github.com/recurziv/haquery) is much better than the go version (Parsec is a godsend + that was my second shot at a selector engine), I will try to port the ideas from there.