work in steering behaviors
work in mobility
- add velocity vector vizu
- tests in steering behaviors
 restore steegin behaviors containement
 work in mobility and steering beahviors
short propath
solve some issues in mobility
fix update from orign master
Merge branch 'master' of github.com:pylayers/pylayers into mobility

Conflicts:
	pylayers/mobility/transit/SteeringBehavior.py
Merge branch 'mobility'