When several cathegories (e.g. licit, spoof) are need for each system
without evaluation scores.

It is used to define custom legends for dev, eval plots

Use same legend for dev and eval hist when the number of legends is
equal to the number of systems. It is still possible to change the
legends of individual histograms by passing 2 * #system legends.

Improvements to new metrics codes

See merge request !70

Various improvements

Closes #41 and #42

See merge request !72

Fix issues with matplotlib.hist.

See merge request !71

Explain that the thresholds might not satisfy the requested criteria

See merge request !69

Change --eval option default and Various fixes

Closes bob.bio.base#112

See merge request !68

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

Titles

See merge request !67

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.

Add prefix aliasing

See merge request !66

Modification of criterion_option

See merge request !65