[zeromq] update to version 4 in rawhide

[Petr Pisar]

On 2014-11-14, Thomas Spura <tomspur at fedoraproject.org> wrote:
> I'll update the zeromq package to version 4 next week in rawhide, which
> will break all existing packages that depend on the current zeromq package
> as there have been quite some changes [1].
[...]
> Similarly, I'd like to retire the zeromq3 package,

Is zeromq4 protocol compatible with zeromq3? And with zeromq2? Or are
they backward compatible?

-- Petr