Upgrades to epee::net_utils::network_address

- internal nullptr checks
  - prevent modifications to network_address (shallow copy issues)
  - automagically works with any type containing interface functions
  - removed fnv1a hashing
  - ipv4_network_address now flattened with no base class

tests/unit_tests/ban.cpp

@@ -33,7 +33,7 @@
 #include "p2p/net_node.h"
 #include "cryptonote_protocol/cryptonote_protocol_handler.h"
 
-#define MAKE_IPV4_ADDRESS(a,b,c,d) new epee::net_utils::ipv4_network_address(MAKE_IP(a,b,c,d),0)
+#define MAKE_IPV4_ADDRESS(a,b,c,d) epee::net_utils::ipv4_network_address{MAKE_IP(a,b,c,d),0}
 
 namespace cryptonote {
   class blockchain_storage;