Made more semantically correct and XML-compliant.

Switched h3s and h1s around to make the page more semantically correct (h1s are
higher precedence than h3s so they should be the top headlines). Moved styles
around to make that happen, and fixed any emergent inconsistencies from such
changes. Added close slashes to empty tags so they are XML compliant.
Optimized hr.gif into hr.png to save over 1KB.
The issue tracker has an "s" at the URL end.
Merge pull request #3 from cbojar/gh-pages

Made more semantically correct and XML-compliant, image optimization and minor fixes.