pScheduler slide deck update

[laeti-tia]

I think the current pScheduler slide deck we use in the workshops would warrant an update, IIRC it dates back from 4.0 mostly.

It starts with the BWCTL comparison and changes that we can probably drop at this point (or just reference at the end). It also lists a few commands that are mostly used in API calls but of no direct use when running manually in the CLI. In general, when used in workshops, this deck should focus on the general architecture and using pScheduler on the CLI, I think that's what is most relevant.

We also need to add the 4.2 new features in it and check if all 4.1 changes are properly integrated. And update screenshots that are existing (the plot-schedule for example now has 6 columns instead of 4).

[laeti-tia]

A new deck is available for review and use in our usual drive.