Fix atom media type
Reformat to 79 columns
Request specific GitHub API version

As recommended by <https://developer.github.com/v3/#current-version>
Use a div as well as main

Opera doesn't seem to respect the CSS .foo for <main class="foo">.  Putting a
div just inside the <main> to provide the class Opera needs to know about.
Tag for metablogging
dos2unix on metablogging
Improve related posts, comments

- Only provide related posts section if there are any.
- Smaller headers on both sections.
- Smaller text linking to related posts.
Reduce padding around related posts / comments