Add themes TeleMark and #knochenmark with updated preview images

This contains the themes TeleMark and #knochenmark with updated preview images corresponding to your [comment](https://github.com/holmar/mark/pull/2#issuecomment-59771544). I hope the font sizes, positions and margins in the preview images are okay now. (I didn't know how to change the previous pull request so I opened a new branch with the changes ...)