Aitk.robots

Major changes:

* requires aitk.utils
* Adjust Playback buttons
* Always inject CSS; clean up watchers
* CameraWatcher takes layout kwargs; move(t, r, quiet)
* Added world.run(background=True)
* world.stop()
* world.status
* display(format)
* get_widget()

Major changes:

* Use World.add_bulb("yellow", ...) rather than World.add_bulb(Bulb("yellow", ...))

Major changes:

* Allow robot.move(T, R) to ignore None values (to control one or the other)
* Changed World.add_bulb() to take args, not Bulb object

Major changes:

* Changed camera angle from 60 to 30
* Changed colorsFadeWithDistance 0.5 to 0.9
* Changed cameraShape from [256, 128] to [64, 32]
* Changed robot.get_pose(), set_pose() and repr to be counter-clockwise positive
* Renamed world.take_picture() to world.display()

Major changes:

* fixed two issues in world.reset()

Major changes:

* camera views are now pixelated rather than blurred
* camera.watch() is now a singleton