remove group attributes and functionalities from pedestrian class

(// TODO should actually be an attribute or a member of a subclass) subclass was not possible because there are several Subclasses of pedestrian (e.g. PedestrianOSM) from which a group subclass would need to extend. Interfaces cannot hold attributes so it would be 20 classes with duplicated code. This is now moving the functionality to cgm. However there is one problem regarding the json attributes in pedestrian, which do no longer contain groupId, groupSize and agentsInGroup.