exit with -1 when error (for travis)
make the ref_tracking_pattern for several robots
draw additionnal lines
add a computation of the minimal distance
use of PQP for the collision check
start to implement dynamic simulation using pqp
simu seems to work with boxes
perform dynamic simulation for several robots (pattern and control only for the first one)
set controller and pattern generator for each robot
add the null controller
update the contact forces (in the world frame)
add message for improvments