Seash should have a progress bar

[aaaaalbert]

There was a recent user request for a progress bar (or perhaps other status indicator) for actions in seash. Indeed, it only prints a summary of what happened after everything is done, or has failed, respectively, grouping the vessels depending on the outcome of the action, e.g. listStarted, listTerminated, etc.

Let's think about a meaningful way to implement this. One (coarse grained) approach could be to poll the parallelize functions on how many of the threads contacting vessels have already finished. Another could be to print more verbosely what is going on behind the scenes, e.g. "Looking up contact information for node X", "Contacting vessel Y", "Uploading file Z", etc.