This reverts commit 9fa8fab864.

Before this pull request, the 404 and 404-search templates where handled
as full HTML pages without the page context (layout).

With this pull request both pages are rendered inside the selected
themes layout. Additionally the 404 template now contains the "search
form" and the homepage link.

All Themes are already updated with the above changes.

Add new theme blog

Move the title, description, and canonical from the head_contents for
better templating. Eg. for Twitter Card or OG.

HTMLy fully supports the HTTPS protocol.

Improve theme

Improve search form + perfomance.

Fix default theme style

Change the default theme style.

Various minor changes for better code readability.

Add author info on post.

Yay! HTMLy was born today.