Have an option to have the paths return their path costs and be able to use that with a replan to compare if the cost have changed "sufficiently" to a parameterized setting to trigger a replan, rather than only when exactly invalid due to collision.

Allows for paths that have become much more expensive to be replanned based on a user-defined metric

Issues to work through:

• If we have the old path and the new path is shorter since it was replanned after some distance was traveled, how to compare these paths "fairly"?
• Probably involves storing each point-costs in the path and using only the still relevant costs
• That would probably involve a change to the ComputePathToPose API
• Where to store this information? In the planner server? That would make it stateful. If the BT navigator? Probably the best option but where? Probably the blackboard
• What's the metric we want to use? I would suggest a percentage change potentially.