Create node at mouse position instead of at originating node position.
New scaling mechanism based on window size.
Cleanup.

Remove entire node.js build process:
o avoid confusing double import of D3 via package.json and lib/ directory.
o vows unit tests were providing limited value; now replaced with tests.html

Remove old experimental files.
Remove old D3 version.
Upgrade D3 to 3.1.10.