freight: add spatial point plot that shows (aggregated) demand capacity of a tour/carrier

[billyc]

from tilmann -

A spatial point plot that shows (aggregated) demand capacity of a tour/carrier.
Or in other words, i click on a carrier (potentially unplanned!) and see where it's demand is (and how much)

no i mean generic. Like:

• load in a Carriers.xml
• show where demand is (no tour plan needed)

one would need the network of course

Maybe it would be easier not to have points but just to colour the links (as CarrierService for example only holds information on the link but no coordinate)

and then a onedimensional colour rank for example with red = relatively high demand and white = no demand