Integrate LaserTowerOfDeath in game client

[PeterBowman]

In addition to the hardware & controller stuff described at asrob-uc3m/laser-tower-of-death#1, another game component must be developed in order to make the turret interact with other players. We aim to assign it the role of a NPC (non-playable character) driven by visual servoing that normally operates in sentry mode, that is, it's supposed to be looking around itself until a player is found, track his motion and try to shoot at his QR.

Game rules should be discussed here. The following questions arise:

1. Define the motion pattern in sentry mode (could be some randomly generated trajectory; keep in mind we can pan and tilt the camera).
2. Usually, you can't identify a robot unless it's facing you, therefore it would be not be possible for the turret to track moving robots nor for said robots to escape once they have been targeted. Idea: just put more QR labels all around the robot...?
3. Can we have a LTOD in simulation?
4. ...

Possibly blocked by #21.