Show items counts on dashboard

Show the total number of items, as well as the number of orders, which are ready to pick, despatched today etc.

These counts could also be displayed in the Overview Of Sales By Channel section, perhaps after the order count - eg instead of just (220) £4600 for 220 orders, we could see (220 / 1000) £4600 to designate that the 220 orders contained 1000 items.

Better yet, display units per hour figures on the dashboard, using data taken from the Picking module.