Simplify demo/demo.html
Remove dot from dagre, some demos broken

Fixes #65
Some initial work to use graph as input to layout.run()
Improve chances of detecting a failure in demo.html with demo-test
Initial work to on d3 renderer
Add arrowheads to directed edges
D3 renderer: draw edges behind nodes
D3 renderer: add support for HTML labels
Add zoom behavior back to demo.html
Rename demo to interactive-demo
interactive-demo: push rendered graph off of the svg border
Add back debugAlignment
Fixup alignment debugger
Fix up minor style problem that would cause some edges to be hidden
Remove some unused demo code
Add json example of tcp-state-diagram
Fix up sentence-tokenization demo for new renderer
Add some color to tcp state diagram demos