pose_follower: Driving backwards even with allow_backwards=false

[nxdefiant]

Hi,

the pose_follower is driving backwards with non holonomic robots even when the parameter allow_backwards is set to false.

I think that PoseFollower::limitTwist() is missing a check for this condition, e.g. the following should help:

if (!allow_backwards_ && res.linear.x < 0) {
	res.linear.x = 0.0;
}