First select a period on Documents view.

       Then compute a graph chosing one distance (distributional or
       conditional).

       Then in Graph Explorer view (TinaWebJS), user can get colors of
       node with growth attributes.

       Red nodes are increasing.
       Yellow nodes are decreasing.

       Growth computed with previous period which is equal to the
       selected period in duration (but before).

       TODO: make some tests with Users to validate the fact that
       previous period is not all the corpus but the selected period.