Fast attribute inspection

It's a real pain in the bum having to continually wire attributes up to the viewer node's value input when you want to see a stored attribute in the 3d viewport.

I'd like to request that the user can click the attribute name either in the spreadsheet, or in a new attribute list in the n panel of the node editor to override the value input of any active viewer node until it's clicked again, at which point the value input would be used again.

This would make it easy to quickly scrutnize the attribute values at different points in the node tree.