Force Slave Status for nodes in Multi Master Setup

I would like to request the implementation in the mmmon module of the hability to "force" the status of a given node to be a Slave. (No writes are routed torwards this node).

Today this is accomplished by setting up the global read only flag in the node, but in some situations this is not desirable. (Node A should receive writes from app in node A plus reads from app in Node B and vice-versa)

This could be implemented as a flag in the [server] section.