Makefile related improvements
Extract zoom functionality
Extract addTextLabel and wordwrap
Extract isSubgraph
Extract addHtmlLabel
More consistent use of labelStyle + HTML fixes
Fix up etl-status demo for html labelType
Extract addLabel
Add pan and zoom to interactive demo
Update to dagre 0.5.0, graphlib 0.8.0

This change breaks dagre-d3. We'll be in this state for a while.
Initial rework with nodes and edges rendering
Collapse drawEdgePaths, support edge path config
Reorder groups to put edge paths behind nodes
Add zoom to interactive demo
Initial work on clusters
Initial support for arrowheads
Get graphlib-dot from github
Use basis interpolation for splines
Pick up latest dagre + graphlib
Take the input graph as an explicit argument in render