Fix footnotes in the printed version.

Using "html,body{height:100%}" pushed footnotes off their intended page.
Use a relative size for <code> in print so that it works in headers.
Fix dash-bullets in Prince.
It uses margin instead of padding to indent <ul>s, but it supports ::marker.
Allow Prince to break pages inside of <pre><code> blocks by removing the inline-block style.
Avoid page breaks just after headings and inside function specifications.
Let <cxx-definition-section> be used from an include, and fix its shadow-dom styling.

Also fix its description.
Add instructions to preview through an HTTP server and use Prince to generate PDF.
Remove <link rel="import">s when publishing.
Bump Polymer version to 0.2.4.

This shouldn't need any code changes.