default change of --eval option

Was True, is not False, so tests and doc must be modified accordingly

Remove threshod vline form histogram plots

option

plots

Before only one title could be changed even when two plots where in the
figure and title was augmented with (development/evaluation). Now the
titles can be entirely defined.

Correct display of available criteria

Modify the display of histograms: now can use subplots to display several histograms on one page, can no longer display both dev and eval histo at the same time, can control the number of columns in the legend