Provide Query Paramater to avoid copying Value's data?

[kevina]

When NextSync() is used it is safe to avoid copying the Value's data. This will help mostly with go-ds-leveldb queries see libp2p/go-libp2p-kad-dht#39.

@whyrusleeping Do you think this is a good idea? If this paramater is provided it will be an error to call either the Next() or Process() methods on the results.

[kevina]

From IRC:

whyrusleeping: kevina: yeah, lets punt on doing the zero-copy values for now
whyrusleeping: I definitely want that at some point, but lets not rock the boat too much here
whyrusleeping: the reason i'm more hesitant on this one is that misuse of that feature can lead to some pretty subtle bugs