Use of waypoints_df.drop() result is not assigned (route_planner.py:794)

[moraygrieve]

Describe the bug
In route_planner.py line 794 waypoints_df looks to be a pandas dataframe, so calling drop returns a reference to the new dataframe with the elements removed, rather than removing them in place.

  # Current (broken) — DataFrame unchanged                                                                                                
  waypoints_df.drop(idx)                                                                                                                  
                        
  # Fix                                                                                                                                   
  waypoints_df = waypoints_df.drop(idx)

The pandas documentation states that drop "Returns DataFrame or None DataFrame with the specified index or column labels removed or None if inplace=True." In this case inPlace is not given, and so defaults to False.