Export treeview to HTML

This code takes a treeview as parameter and generates HTML that exactly represates this treeview. This includes indentation, images, bold-text, etc. I couldn't find any good code that could generate the right HTML (there were lots of errors in most of the code) so I decided to make my own version. This code is based on code by Chetan Sarva and for a little bit on Manu Bangia.