As described in #147 (closed), this development improves the plot titles when aggregated data spans multiple years, displaying the correct years while avoiding repeating them when it's not necessary. The improvement has been done for subseasonal, seasonal and decadal data.
It also includes a refactoring of the code in plot_ensemble_mean() and plot_most_likely_terciles(); a new function get_plot_time_labels() has been added (modules/Visualization/R/get_plot_time_labels.R).
I have added a category of unit tests ("Utils") to include unit tests for utility functions. get_plot_time_labels() has a unit test already.
FYI @nperez
Victòria