Get rid of leading underscore convention in non database storable Process inputs

[sphuber]

Originally the convention was that in order to mark Process inputs as non database storable, one had to use a name with a leading underscore. We now have a proper mixin, WithNonDb, for the InputPort which adds the non_db attribute, which when set to True indicates that it is not to be stored as a Node in the database. Old default work process inputs such as _label, _description and _options will have to be updated by removing the leading underscore and just use the attribute

[muhrin]

Done in PR #1105.