View that makes Javascript trees. The trees have expanding and
collapsing nodes. call js_init() with the button images and default
open/close policy during process
Methods Details:
Write a leaf node to the output at the current tree level.
Write a non-leaf node to the output at the current tree level, and
start a new level.
Finish a non-leaf node, and close the current tree level.
Writes the end of the tree.