Smoothed how the TrafficManager does turns

[glopezdiest]

Description

Changed the target location used by the TrafficManager control to smooth the way turns are performed.

Currently, the road is divided into waypoints every 5m, reduced to 2-3m at turns. The MotionPlanStage selects one of these waypoints and uses is as the target. This creates sudden changes in the target yaw, making the control less smooth.

This PR makes it so that instead of targeting a specific waypoint, it interpolates between the two closest ones to that target distance, picking a location in between. The PR also changes the angular metric from the dot product to the angle. It doesn't really make that much of a difference control wise, but the dot product has a non-linear relation with the steering, while the angle has so it adds a bit of robustness..

Where has this been tested?

• Platform(s): Ubuntu 22.04
• Python version(s): 3.10
• Unreal Engine version(s): CARLA's UE4

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