Improve the way we ask for operational attributes

When you want to see Operational Attributes, you may have to modify two parameters :

• one on the connection (then the connection will be closed and reopened)
• one in the entry's menu

It would be convenient to add such a capacity in an entry contextual meny (ie, right click on the entry on the browser) to expose those values. of course, if you switch to another entry, then you won't see the opattrs unless you do the same action.