Show monthly units sold when hovering cursor in sidebar graphs

[guto8797]

Hovering your cursor over the points in the side graph will show you what your revenue was in that month in $, and how many fans you gained/lost on that month in the fans graph.

I would suggest the graph also showing how many units were sold on that month in the same tooltip. Right now you can hover over the graph itself and see total units sold for the game, but no way to see how many sold in that specific month, at least in the sidebar graph.

It would help gauge the effectiveness of discounts/conventions/marketing on sales.