Kate: More eye-candy

Two years ago we had the KDE conference in Ludwigsburg, Germany. At that time, Martijn Klingens committed a patch to show trailing spaces in Kate. I just change the visualization a bit, the change is in for KDE4 :) Tabs are marked with a ‘ยป’ character, and spaces with a dot. On the left you can see the old and on the right the new version; Here is a screenshot: