Translate splash screen

Adds translation links to the splash screen. 

In order to force refresh of the splash screen, actions that handle the translation links do a sequence of remove / initialize colorbox. That broke the bit of logic that was there to ensure the correct positioning of the close button (little circle in right top) on the landing screen. That logic was there because the older version of colorbox we were using did not allow to set a class name on the particular colorbox instance to be able to style it appropriately. Upgrading colorbox fixed that, so I could remove that logic and replace it with css definition. Unfortunately, it also added a white outline to the close button which I seem to be unable to remove.