Visualizations of some important internal/intermediate pipeline planning states

To improve the understability of the pipeline planning stages it would help to visualize some intermediate planning states like:

• PCollection lineage. (visualizing the output-pcollection-targets structure)
• MSCRPlanner's planning Graphs before and after the split up of dependent GBK nodes
• RTNode hierarchy along with the Input and Output configurations as persistent in the Configuration before the execution of the pipeline.

Most of the information can be intercepted in the MSCRPlanner#plan() method.