Refactor: hypotheses tracing refactors in interactive hypothesis space correlation plot

[ramyamounir]

There are a couple of possible refactors in the hypothesis space correlation plot. These were left as follow up work after PR#16

• We can have a class that decrements and increments location pairs (episode and step). It would have the ability to go to the next episode if at the last step, or go to the previous episode if at the first step of the current episode. This functionality would be refactored from CorrelationPlotWidgetOps, HypothesisMeshWidgetOps, and in HypothesisLifespanWidgetOps.
• We can also have a class to trace a specific hypothesis backward and forward. We have some refactored helper functions, but we can create a class that just traces a single hypothesis backward and forward using these helper functions. This functionality will be refactored from HypothesisLifespanWidgetOps and HypothesisMeshWidgetOps. With the introduction of hypotheses resampling, I imagine this class will be used in many future visualizations.