Extended EM support for Persons

[awillecke]

Hi Raphael,

we added support for persons in the Environment Model so that persons (equipped or plain) can be perceived with sensors. Also, persons are hidden in the preselection if they are driving/riding a vehicle.

Most changes are regarding the abstraction of vehicle-specific classes including:

• Adding a Controller, that is used by the specific Person- and VehicleController
• Generalized the CarIdentityRegistry
• Generalized vehicles to objects in the GEM

Please let us know what you think about these changes and whether you would like us to adjust the implementation.

Best regards Alex

[awillecke]

I found some smaller issues and added a small scenario for testing the Environment Model. Also, when it is ok for merging, it should handle #295.

[riebl]

Thanks a lot for your great work and sorry for the long time I took to merge your PR!