First step in redesigning the website layout

Switched from XHTML to HTML5. Using larger font sizes. Simplified the language menu and moved it to the footer. Removed some obsolete files.
Improved display of the screenshot slider
Only display the slider at the front page

Other layout improvements. Obsolete files were deleted. Added some new images.
Updated the layout for most of the pages

Removed many obsolute images. Some images were updated. Deleted the screenshots page (the Choose a distribution page now shows screenshots).
Use Font Awesome and jQuery for fancy looks and functionalities

Removed the toggleanswers.js script; this is now done with jQuery.
Removed the AddThis and Flattr widget. Flattr is now a simple link.
Removed the language selection page.
Removed the alternative footer file.
Use jQuery to provide a fancy go-to-top button on every page.
Use jQuery to toggle display of incomplete translations in the footer.
Updated the Credits page.
Updated the settings.php template.
Made some small changes in the API.
Removed many obsolete image files.
Updated the setup page
Added Mousetrap functionality and did some code cleanup
Declare the character encoding in the setup page
Updated the instructions on the setup page
Fixed the display of the footer for rtl
Improved display of the footer on mobile devices
Fixed a typo (HTML tag mismatch)
The acronym element is obsolete. Use the abbr element instead.
The acronym element is obsolete. Replaced it by the abbr element in all .po files.
Updated the Link Buttons page
Updated the Legal terms page
Marked a new string as translatable
Use 'translators' instead of 'i18n' for translation comments

Updated the Makefile in the process. The PO files were also updated.
Made some strings untranslatable
Missed some acronym tags in the .po files