Catch "file editing" browser permission errors #117
Description
I just noticed that downloading files fails on my chrome browser because it is company managed and doesn't allow editing files.
NotAllowedError: Failed to execute 'showSaveFilePicker' on 'Window': The request is not allowed by the user agent or the platform in the current context.
When using the ediTDor without an intermediary to save the TD/TM to this might cause problems. For "Download" I would try to fall back to simply dowloading into the downloads folder. For "Save" we would have to notify the user that he has to check his browser settings for the right permissions.