- Addition of ReplServerStartDSMsg now sent to a DS connecting to a RS 
in handshake phase instead of a ReplServerStartMsg. ReplServerStartDSMsg 
contains same thing as ReplServerStartMsg but also contains

  - replication server weight

  - number of ciurrently connected DS on the RS

  => both will be used for future new RS choice algorithm



- Addition of a StopMsg sent:

  - when any entity (DS,RS) is closing a connection (sent just before) 
with a peer

  - when DS finishes phase 1 of handshake (was gathering RS info for RS 
choice so sent just after new ReplServerStartDSMsg is received)

  => both are used to distinguish between a proper connection closure 
(no message) and an unexpected one (error log)



- Compatibility between protocol V4 and V3 (and before)

  - changed MonitorMsg to never be created with a protocol version

  - MonitorMsg now always sent with publish(msg, version) (publish 
method without version was used so bug)

  - TopologyMsg now always sent with publish(msg, version) (publish 
method without version was used so bug)