REVERT: Allow/mandate greater routing depth to obviate the need for multiple waypoints for ship routes pending assessment as to whether this is viable in performance terms.
FIX: The "traffic" graph in the city list window gave an inaccurately low number. This is now the correct number, being the sum of all individual cities' "traffic" graphs.
FIX: The "traffic" graph in the city list window had the old colour rather than the new colour for "traffic" in the city information window.
VERSION: Increment to 11.20
Merge branch '11.x' into 12.x

Conflicts:
	simversion.h