* Fix broken links in update posts
They were using relative links still which became invalid by moving
directories. It's better to link stuff absolutely anyway.
* Remove unused 'secure' registration and login pages
* Remove obsolete parse.py
* Use templates better to remove a ton of code duplication
Where it made sense I converted HTML pages to Markdown to ease writing
and discourage custom styling as much as possible. These pages can still
use custom HTML when necessary, and some do, but they are easier to read
and understand now.
