[testing] Add a basic test for submarine robot
[actuator] Fix destination actuator to work in 'velocity' mode
[data] Remove logic from submarine
[data] water-1 is set to 'no-collision'
[builder] Make robot more consistent from a point of view of physics

Make robots 'rigid body' when possible, 'dynamic' otherwise. Remove
physics properties of child when necessary / possible.

Now, all robots must be able to run in 'velocity control', at exception
of:
    - PR2
    - Human
    - Quad2012
[builder] Set by default scene.game_settings.physics_step_sub to 2

In this way, the physics is more realist. In particular, it seems to
help the stabilization of ATRV
[builder] Adjust configuration of segway
[testing] Adjust friction test following physics setting change
[actuators] Switch by default to controltype Velocity

Fix #117 (finally) :D
[actuator] Fix waypoint actuator in velocity mode

While here, improve a bit its behaviour when the robot is near its goal
[testing] Adjust several values to pass tests