We already patch ZEO4 with TCP_NODELAY patch (see 5cf4cf1f "ERP5:
enable TCP_NODELAY for ZEO") and we will need to backport more patches
to ZEO4 branch for wendelin.core 2 to work correctly.

It's not only software/neoppod which uses ZEO, and it is not convenient for
all other software-releases to inherit from neoppod to use correct
version and build of ZEO egg. For this reason factor out details of ZEO
egg building into component/ZEO and let users use ${ZEO:egg} where ZEO
is needed. This way ZEO will be correctly installed for all users.

This patch should be a non-functional change. We switch to
nexedi/ZEO@5114f909 revision which corresponds to ZEO 4.3.1 +
TCP_NODELAY.patch

Adding other patches to ZEO4 needed by wendelin.core 2 will be done as a
separate step.