Implement series numbering
Add menu bar
Implement quit action for the menu entry
Implement save image action for the menu entry
Separate saving image from saving data
Reimplement obtaining and getting results

Results are now set by the "Schedule" button,
and on doing so, the chart is redrawn.
Implement new schedule action for the menu entry

Also, change the structure to accommodate the new approach
(checking whether the results are not null and, only then, drawing)
Implement saving to and loading from a file
Implement save data/load data for the menu entry