Fix in setSvgString() for images with no href (images in pattern#gridpattern don't seem to have them)

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2497 eee81c28-f429-11dd-99c0-75d572ba1ddd
Correction for r2497 - namespace had changed from 2.6 branch, sorry, didn't spot it

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2498 eee81c28-f429-11dd-99c0-75d572ba1ddd