Compute HTER using FMR and FNMR

Closes #48

See merge request !81

Consider non 1 values negatives

See merge request !80

Metrics

See merge request !78

titles for histograms.

Add a command for multi protocol (N-fold cross validation) analysis

See merge request !79

dd lines for dev histograms

See merge request !77

Histo fix

See merge request !76

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

Fix issue with histo legends

Closes #47

See merge request !75

Bins histograms

Closes #45

See merge request !74

Histogram legends

Closes #44

See merge request !73

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