Fix for 4096 MonitorMsg is not compatible with replication version

This fix restore the compatibility by using either format depending
on the protocol version.
After this fix the trunk is now compatible with 1.0 and 2.0
but not with 1.2 since there is no way to make the difference between the 
2 versions of the replication protocol (1.2 and 2.0 both use version 2 
of the replication protocol but don't encode MonitorMsg the same way)

This fix also add a trick in the schema backend so that the schema
from 00-core is not replicated.

Gilles