Fix vehicle insertion and removal

[paulheinr]

Currently, vehicles drive all the way down their last link before getting removed. Similarly, after insertion they drive all the way of the first link.
This is for sure not consistent with the current MATSim implementation.

• check the implementations of MATSim
• Adapt the current implementation (think about this wisely as it might cause problems with drt pickup locations)

[frievoe97]

Currently, vehicles travel to the end of the link during an activity and then travel down the link again after the activity.

This is how it should be (MATSim default): After the activity, the vehicle is placed in the buffer (each link has a buffer where vehicles that can leave the link wait).

Currently, no buffer is implemented and vehicles are only stored in the queue in LocalLink.

MATSim reference (dsim): org.matsim.dsim.simulation.net.....