fix code blocks on narrow screens, change post extensions

- Code blocks can't be in tables or they extend past the body width.
  Workaround by using floated line numbers instead.

- Fix typocode CSS

- Change post extension from .html.md to .md. This makes URLs without
  extensions work with harp server again. This change works now that
  article titles never contain periods.
use font awesome for twitter and rss icons, splash some colour on them
wrap article headers so they don't extend past the body width
style blockquotes
comment webkit transform hack for GPU rendering
don't underline footer link
ok fine ... I added a damn "about me" page
tweak style, add a symbol to denote the end of content