Render H1 elements added via autoHeader as anchors

[jhildenbiddle]

When the autoHeader option is set to true, the following HTML is generated:

<h1>Title</h1>

But when an h1 tag is found in markdown, it is converted to the following HTML:

<h1 id="title">
  <a href="#/?id=title" data-id="title" class="anchor">
    <span>Title</span>
  </a>
</h1>

This inconsistency creates a few issues:

1. These elements behave differently, but they shouldn't.
2. These elements may not look the same if theme authors are using the additional attributes and/or HTML tags from the second example as hooks for styling
3. These elements cannot be processed the same way by plugins

Summary: Render elements added via the autoHeader the same as header elements found in markdown.

Thanks!