-PuPy.RobotCollector has optional argument vars with a list of variable names that are written to the log file (loosely tested).
-PuPy.RobotActor has child as optional argument (makes sure child is always callable)
-PuPy.RobotActor has member method _get_initial_targets that returns a target iterator as in __call__
-PuPy.WebotsRobotMixin uses actor's _get_initial_targets method instead of calling the actor before the run loop.
-refactored all supervisor checks. They are now composed of two subclasses, one for the check, one for the action to be executed (loosely tested).
-minor changes
Nico: world_builder.sh can take additional arguments for webots
RobotActor: included built-in signaling chain through method signal(msg, **kwargs).
This replaces the event_handler and makes usage easier (event_handlers can still be used). Mind that all Emitter-Receiver signals from the Supervisor are broadcasted to all actors in the chain!
added collector OnlinePrinter (working) and OnlinePlotter (not yet working)
Merge branch 'nico'
Several new features, e.g. RobotActors are arranged as parent-child-chain with broadcast methods...
Merge branch 'master' into aiLab

Conflicts:
	PuPy/webots.py