[MERGE][0.19] change the pack interface to use tuples for names

[John Arbash Meinel]

John Arbash Meinel has voted approve.
Status is now: Approved
Comment:
Is this okay for 0.19? Since the wire format is the same, it seems 
reasonably safe whenever. Though I would hate to have to worry about 
function compatibility (since you need a bunch of new functions for the 
tuple versions, and you have to deprecate all of the single string 
versions)

(So I would *like* to see it in 0.19)

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C1186542271.30707.51.camel%40localhost.localdomain%3E