ADDED: - new callback post_SlaveStateChange so that a master can monitor the state of its slave nodes using a heartbeat.
* * *
CHANGED: - added missing export for _post_SlaveStateChange (for revision #679)

Authors :
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Edouard TISSERANT (www.canfestival.org)
Francis DUPIN (LIVIC)
Laurent BESSARD (www.canfestival.org)