#63 Redesign the dashboard

This commit contains some serious changes:

- Bugfixes for the menu
- Redesigned bans, options, maintenance and permissions page
- The Dashboard uses now HTML5 instead of XHTML 1.1
- Updated some language files (however, they still contains not used
lines
- Lot's more

Note that the options page contains a tab system at the top of the page
(which is broken). This will be used in another commit.