Implemented writeNetworkDictCallBack test in TestMasterSlave example. Fixed callback assignement race condition in sdo.c.

Post_sync have to be called even if in pre-op state. Fixed.

Now, setNodeId does change TPDO and RPDO CobId without testing previous CobId in order to avoid confusion. Standard does not says when 'default value' should be applied. See DS301 - Object 1400h - 15FFh: Receive PDO Communication Parameter page 108.