Signal when total demand is greater than total capacity

In order to visit all customers without breaking capacity constraints the user needs to add vehicles. As more vehicles are added the total driving time rises. People find this confusing because they expect the solution to improve.

To avoid the confusion, let's display the capacity usage to make it clear that vehicles needs to be added if demand exceeds the capacity. Only when there is enough capacity we can start watching how the routes are being optimized and the driving time goes down.