Add block content_title to index.html
Add html title to article.html
Add templates extending base.html

archives, categories, tags templates adapted from simple theme.
Add templates extending index.html

author, category, tag templates adapted from simple theme.
Add <ol> to archives.html

Archives.html is now similar to index.html. Which I could extend from
index.html instead, but archives is using another loop: `for article in
dates`.
Some cleanup
Fix incorrectly closed tag
Add pagination.html template
Add page.html template