Making PolarRoute-server compatible with latest PolarRoute and MeshiPhi versions

[thomaszwagerman]

Specifically updating how evaluate_route works with PolarRoute changes to route_calc api:

# From
calc_route = route_calc(route_file.name, mesh_file.name)

# To
calc_route = route_calc(df, from_wp, to_wp, mesh.json, "fuel")

Also removing all TempFile related code, as now longer required for new API.

[davidwyld]

I appreciate this is still in draft, but looks good so far, I'm very pleased to finally be getting rid of the need to deal with tempfiles now we can use the python interface more directly.

Feel free to make any other improvements to this function you feel are necessary.

I'm sure you will, but don't forget to restrict the polar-route version in the pyproject.toml from this point.