More visualisation edits. tree.html now works well and spaces itself out well. Currently trying to get screenshots displayed.

	new file:   app/d3/LICENSE
	new file:   app/d3/d3.v3.js
	new file:   app/d3/d3.v3.min.js
	new file:   app/screenshots/thumb.png
	modified:   app/simpletree.html
	new file:   app/thumb.png
	modified:   app/tree.html