new docs, added fixed parameter to nodes
added icons for new examples. minor tweaks (code styling)
added hierarchical layout
Merge remote-tracking branch 'origin/alex_dev' into develop

Conflicts:
	docs/graph.html
Updated intro
small doc change.
Updated history
Merge branch 'alex_dev' into develop

Conflicts:
	src/graph/Graph.js
Updated history
Cleanup some unused code