Db cursor as range

[Andrea Fontana]

Check this original post: 
http://forum.dlang.org/thread/bqimjjyjnjnzmkyakiit@forum.dlang.org?page=1

Now they add a function to save db cursor, so I can implement it 
as struct or add a .save() method.

I don't know if it works fine. Data could change - from outside - 
even during traversing, of course. If I save cursor, next time it 
could give different results. I wonder if this is accettable for 
a range implementation...