Comment 0 for bug 1021096

We should automatically give headings an ID with their title in it.

For example, the following text:

Example Title
-------------

Should come out as:

<h2 id="example-title">Example Title</h2>

That way we can easily link to specific bits in the docs like a section on a longer HIG page. If needed we could always prepend "heading-" or something to make sure it's unique, and of course we'd want to drop special characters.