Add 2 media queries + experimental icon button

Medium size: hide header subtitle and post descriptions.
Small size: hide post dates and fix header.
Experimental: On small size, pages in header are replaced with list
icon, but it doesn't trigger anything.
Remove list button for menu
Clean up main.css

* Reduced comments
* Grouped my styles together
* Closed media queries with }
* Indented my media queries
Add code highlighting
Change to capital hex
Style <pre>
Include pygments.css in main.css
Use native.css as pygments.css
Change pygments.css to own colour scheme
Cleanup CSS

Reorder some atttributes alphabetically
Remove underline in pygments.css
Move some elements around in css
Add styles for several elements

`h2`, `h3`, `h4`, `blockquote`, `code`, `pre`, `table` and footnote are
now all styled
Merge pull request #6 from peterdesmet/dev

Dev