yield for vehicles that finished parking and want to re-enter the road

[namdre]

at the moment, there is only code that enables cooperation by vehicles that themselves want to park at the same parkingArea (MSParkingArea::notifyEgressBlocked).

In addition it would be nice if there was similar behavior as in lane changing:

• configurable desire to change to another lane
• configurable desire to adjust speed and open up a gap

A straightforward implementation would be to inject parking-egreess vehicles into the "is there a blocked leader" check of the lane changing model (firstBlocked or lastBlocked)