Re-factorize / improve `PlotVariables()` function

[rmadar]

Re-factorize / improve `PlotVariables()` function

[rmadar]

After breaking down the hook normalization, hplot, and hstack, I lost a factor 3 of time ~6ms -> 21ms (for 60 variables). This must be understood before going further ...

[rmadar]

This was a bug induced by the benchmark code: variables were duplicated, and the variable indices were based on their names. So about 3 less variables were plotted in the old version. Once corrected, we have the following scenarios.

(Note that the time includes event loop, that's why the total time per event decreases : the plotting time relative contribution get smaller when event loops are larger).

New plotting: w/ concurrency

Running for nVars = 60
  -> 0.5M evts: 7.43 ms/kEvts
  -> 1.0M evts: 4.80 ms/kEvts
  -> 2.0M evts: 2.97 ms/kEvts
  -> 2.5M evts: 2.36 ms/kEvts

Old plotting: w/o concurrency

Running for nVars = 60
  -> 0.5M evts: 21.68 ms/kEvts
  -> 1.0M evts: 11.85 ms/kEvts
  -> 2.0M evts: 5.85 ms/kEvts
  -> 2.5M evts: 3.98 ms/kEvts

Plotting but hplot.Save(fig, w, h) command disabled

Running for nVars = 60
  -> 0.5M evts: 1.76 ms/kEvts
  -> 1.0M evts: 1.74 ms/kEvts
  -> 2.0M evts: 1.81 ms/kEvts
  -> 2.5M evts: 1.74 ms/kEvts

[rmadar]

Every point were addressed: closing.