Sankeys with Cycles

Features

• Sankeys in NetworkFrame now accept networks with cycles and render them using Tom Shanley's d3-sankey-circular layout.
  
• Add a relative tag to bucketized summaryTypes in ORFrame to allow the visualization to display the relative size of the data (with the max being the max value for that category) as opposed to the default behavior which sizes graphical elements by the max value across all categories.

Fixes

• Margin has been fixed so that passing a numerical value is properly treated as margin for all sides.