Make json attributes spelling consistent

The plan was to use underscores for the internal data representation of the scopes. I have extended this to the directory names of the internal data format.

These changes don't allow importing of previously created system descriptions. Loading them results into an unexpected error until the versioning [checks] are implemented.

Following these changes internal scope names have to be converted by the method `Cli.convert_scope_names` if they are presented to the user.