new parameter type "enum"¶

it has been discussed to add a new parameter type "enum", to store and address enumerated lists (e.g. menus)

- items can be addressed through index number or item's name (symbol)
- the list of all available items are stored as /range attributes and can be changed dynamically and queried remotely
- we need a notification system so that jcom.nodeview is informed if the list of items is changed...
- ¿¿ maybe we want to return the current item to the world as an index number OR the item's name... how do we manage that ?