Relative paths broken depending on how you access a tutorial

[kdclang]

Images relative path are incorrect if you access a beginner tutorial NOT from the yrtoolkit/index.html file. If you try to put in the full tutorial link for a non-YR tutorial, the relative paths don't work. They should be able to be stand-alone, as it doesn't make sense to give access to all tutorials (YR, Malden, Beginner) in one menu. We could potentially put all non-YR tutorials in a menu, but Malden and YR won't have any meaning to a generic user.