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.

Modification of criterion_option

See merge request !65

Correct display of available criteria

Fix semilog plots for non numpy arrays

Closes bob.bio.base#117

See merge request !64

Enable semilogx option in roc curves

Closes #40

See merge request !63

Improve legends in histograms

See merge request !62

Title and histograms subplots

See merge request !61

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

Bugfix

See merge request !60

Add min-far-value option, rename -l (already used) to -Z, change the way linestyles are handled and make use of them optional

Bug fix: incorrect input file reading

See merge request !59

Change variable name form criter to criterion

See merge request !58

Extend bins number option

See merge request !57

Fix error in context name

See merge request !56