Use different methods to initialize the tree (Ajax, embedded <ul>,
embedded JSON).
Also distinct nodes contain custom data using `data="..."` attributes.
See the LoadData Tutorial
for details.
Load from embedded <UL> markup:
simple node (no explicit id, so a default key is generated)
Define key and tooltip using 'id' and 'title' attributes
item2 with html inside a span tag
this nodes adds class 'nolink', so no <a> tag is generated