svg: rewire badges in header navigation
- produce only one punched icon with canvas
- use css filters to change color to white on active/hover (native for webkit, svg fallback for firefox, too bad for IE)
- add badges via css and data-attributes so we have to render the canvas for each icon only once

re #5007


git-svn-id: svn://develop.studip.de/studip/trunk@32260 c5b85792-5220-0410-ad23-ed5b6b8ad999