Extend to allow for node lookups for multiple selectors

At present if I have the following html:

<html>
    <body>
        <p id="description">This is a description</p>
        <p id="secondary-description">This is a secondary description</p>
        <p id="not-a-description">This is a secondary description</p>        
    </body>
</html>

If you wanted to get description and secondary-description you need to do:

    var nodes = html.CssSelect("description");
    var nodes = html.CssSelect("secondary-description");

Ideally you could use a call like:

    var nodes = html.CssSelect(new string[] { "description", "secondary-description" });

rflechner / ScrapySharp

Extend to allow for node lookups for multiple selectors #11