Find a better way to save our python workflows

[thompson318]

The lesson on instance segmentation introduces saving python workflows to enable repeatability. We currently use "%save measure_percent ~0/" to save our console session. This isn't ideal as it then requires editing to make a "nice" python script file. The script-editor plugin would allow us to introduce nicer coding style but currently has no nice output. There's an issue to add this to the plugin, so if that gets fixed we could re-jig the lesson to use the script-editor plugin instead of the console.
haesleinhuepf/napari-script-editor#7