A channel provides no way to specify whether we stopped sending data
because of an error or because there is no more data.
Therefore, make Odb.ForEach() take a callback with which the user is free to
do whatever they need, letting us return en error.
This is the most common way of having an id that's not in Oid form, so
let's make it the "default" and rename to NewOidFromBytes() the one that
takes []byte.
The interface to these streams should be what you expect from Go, and
both have Write and Close functions so they implement
Reader/ReadCloser and Write/WriteCloser respectively.
Carlos Martín Nieto
Claudiu-Vlad Ursache