add isloopbackIPAddress to code/nel/src/net/inet_address.cpp
add IPv4&IPv6 loopback IP addresses to localAddresses
In code/nel/src/net/unified_network.cpp:
replace is127001 calls by isloopbackIPAddress
change wrong comments about default network id (nid = 0xFF)
When the selected connectionId is not valid
warnings are not triggered anymore when using default network (nid = 0xFF): the logs were full of warnings and the server was lagging
When nid = 0xFF, the new connectionId is stored into DefaultNetwork
When nid <> 0xFF, the new connectionId is stored into NetworkConnectionAssociations[nid]
