Support all CSS `selectors-4` selectors

[yisibl]

There are currently many selector tests that fail.

• :nth-col() feat: add :nth-col() and :nth-last-col() selectors #302
• :nth-last-col() feat: add :nth-col() and :nth-last-col() selectors #302
• :nth-child(An+B [of S]?) Support :nth-child(An+B of S) selector #392
• :nth-last-child(An+B [of S]?) Support :nth-child(An+B of S) selector #392
• More…

e.g.
https://www.w3.org/TR/selectors-4/#the-nth-col-pseudo

:nth-col(odd) {
    width: 10px;
}

:nth-col(2n+1) {
    width: 20px;
}

:nth-last-col(odd) {
    width: 30px;
}

:nth-last-col(2n+1) {
    width: 40px;
}

[devongovett]

As far as I can tell, there are no browsers that implement these yet, and no way to polyfill them with pure CSS. So I don't feel too much rush at this point. Would be easy to add to the parser though if someone wants to go for it!