Add per-iteration keywords from fps convergence

In order to drive the GUI updates we need keywords marking the end of each fps convergence loop and the end of the entire convergence loop. I propose the following:

fpsConvergenceStep=$visit,$subvisit,$iterationsPlanned,$iterationsDone,$cobrasDriven,$cobrasCompleted

fpsConvergenceDone=$visit,$iterationsDone,$cobrasDriven,$cobrasCompleted