template: language menu rework

• Removes right alignment because it does not fit the page flow.

• Converts languages to a list with inline style. This is semantically better (for screen readers etc.) and provides a nicer separation.

• Changes the marker of the active language from 'not a link' to a class. This makes styling easier and is semantically more correct.

Signed-off-by: Marco Neumann <marco@crepererum.net>