Generate anchors to properties and methods

Hey @redmunds, @peterflynn

This is an initial approach to get named API entries so they can be targeted using anchors (#73). It's not the full solution, but I think it's already quite useful.

I'd like to get this in so you can use it when generating the docs for 0.42. After my vacation, I'll polish the missing details using #79.

What do you guys think?
No special reason for it to be an `<i>` tag... will switch to `<span>`. The technique comes from Github markdown headers... this way, it's easy to click on it and copy/paste the url. I also like it ;)

About the `id` over `name`... that's a more complex issue. In [6.6.9 Navigating to a fragment identifier](http://www.w3.org/html/wg/drafts/html/master/browsers.html#scroll-to-fragid) at some point the algorithm goes as:
> 5.- If there is an element in the DOM that has an ID exactly equal to decoded fragid, then the first such element in tree order is the indicated part of the document; stop the algorithm here.
> 6.- No decoded fragid: If there is an a element in the DOM that has a name attribute whose value is exactly equal to fragid (not decoded fragid), then the first such element in tree order is the indicated part of the document; stop the algorithm here.

I went with `name` because `id` is also expected to map the elements to variables in the global scope as per http://www.whatwg.org/specs/web-apps/current-work/#named-access-on-the-window-object and didn't want to have all those lying around. 

On the other hand, the `a` element in HTML5 spec doesn't have a `name` attribute, so not sure if this should force us to go with `id` or use some other element along the way.

What do you think?