Correctly handle multiple waypoints in our adding/removal code

[logbasem]

While you can add >1 waypoint, only the newest one shows up on the map.

Discussion

In the background, the code only manages one waypoint at a time. So, when you try to remove the new waypoint, it actually removes the old (invisible) one first.

This makes the map feel kinda buggy.

• Ask @carsonburnett for more information.
• This may or may not be needed depending on what the other subteams need.

Checklist

• Render all waypoints present on the map
• Correctly add and remove a waypoint on the map when it has multiple waypoints
  • You could iterate over all waypoints on the map before doing operations.
    • Then, just use the newest one!
  • Or, you can handle removing waypoints by showing them in a list.