RFC on range design for D2

[Benji Smith]

Leandro Lucarella wrote:
> Andrei Alexandrescu, el  9 de septiembre a las 10:30 me escribiste:

>> I'd like to go with:
>>
>> r.first
>> r.last
> 
> Much better, thank you! =)
> 

Maybe:

r.head
r.tail

Also, I'm not crazy about the "isEmpty" name. Given the use of 
"getNext", I think "hasNext" is a more natural choice.

--benji