I added a new plugin that enables force layout (graph) visualization on top of the existing set of visualization (bar chart, pie chart, scatter, etc.).
The current visualizations use the nvd3.js package which doesn't include the force layout component, so I used the "raw" D3.js package to generate it.
I almost didn't change any of the existing code, mainly added my code.
In order to use the graph visualization, after running the SQL statement, the user needs to choose the columns which represent the source and destination nodes, and also the source and destination groups (which determines the color of each node).
The capabilities I currently added are zoom, pan, dragging and node's tooltip.