timers_unix.c : remove sigint and sigterm catch
sdo : Allow multiple servers
The sdo transfer struct is not anymore referenced by server's node id but by
client or server number in the OD. Node id is not relevant in SDO transfert.

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