Uniformize Movements / Move actions

[jotak]

Currently move actions (GoTo, ErraticMove) just create Movement object and bind it to AI.
However we need to :

• stop a movement when the action is stopped
• starting a new movement (like for a new task) should cancel any previous move

Probably the Action should implement itself the Movement

[jotak]

• "GoTo" is now ok (neither a movement, not an action)
• Still need to transform "ErraticMove" into an action
• Interface "Movement" won't be used for now (maybe later for kind of "physical" movements)