diachronic view - add axis labels #39
Description
Add axis labels to charts.
On x-axis: release date.
On y-axis: metric and unit (if applicable); e. g. "wall time in minutes" or "Pages per minute".
Labels must be shown when plot is enlarged, but can be ommitted when in preview (for a cleaner look as many charts are shown).
Align the label centered on the axis.