Add a TargetChangerAlgorithmType Enum to
AttributeTargetChanger to select the needed behaviour.
During TargetChangerController init instantiate the
TargetChangerAlgorithm and redirect update to the algorithm.

Default algorithm SELECT_LIST: nextTarget any number of
targets from  [1 ... N], probabilityToChangeTarget exactly
one element between (including) [0.0, 1.0]. If change takes
place pedestrians targetList is replaced with nextTarget