If the user clicks the "Save Script" button below an operator's
python script, and then chooses to save the script somewhere,
save the description.json file next to it (where the filename will be
the script name with a `.json` extension) it if the following conditions
are true:

1. The JSON description for the operator is not empty
2. The file does not already exist
3. We have permission to write the file

Maybe we can discuss this logic...

Signed-off-by: Patrick Avery <patrick.avery@kitware.com>

This will hide the "Additional Parameters" for the reconstruction
section if, for instance, a parameter with a test rotations tag is
present.

Signed-off-by: Patrick Avery <patrick.avery@kitware.com>

Just to make it much clearer what is going on, if the description
file exists, ask the user if they want to overwrite it. This will
make things much more intuitive as to when the file gets overwritten.

Signed-off-by: Patrick Avery <patrick.avery@kitware.com>