Pedestrian animation flickering

[dethrace-labs]

Steps to repro:

• Chase a pedestrian until the pedestrian gets to the end of their path.
• Approach the pedestrian slowly - the car must have a speed > 0

In this scenario, the pedestrian flicks quickly between 2 actions - standing still and running away, causing the ped texture to flicker as it changes rapidly back and forth.

This behavior exists in the original game. However, at lower framerates it looks more acceptable. One possible fix is to only flip between actions once it has been more than X (50?) milliseconds since the last action change.

Relates to #118

[dethrace-labs]

A similar issue exists when chasing a regular running pedestrian - their animation frames flip too quickly at > 30fps causing ugly flickering