Currently the `getnetworkinfo` returns something like: 

```
"localservices": "0000000000000449",
```

Manually parsing this consistently gives me a headache (see also https://github.com/sipa/bitcoin-seeder/pull/77).

It would be useful to parse this and show the right combination of `NODE_NETWORK`, `NODE_GETUTXO`, `NODE_BLOOM`, `NODE_WITNESS`, `NODE_NETWORK_LIMITED` and `NODE_COMPACT_FILTERS`. In addition the help text for `getnetworkinfo` could be expanded to mention the right BIP numbers for known flags.

There is some ad hoc parsing to populate e.g. `localrelay`, etc (?).  Their help text could also refer back to `NODE_GETUTXO`.

See also: https://en.bitcoin.it/wiki/Protocol_documentation#Network_address
if(network == NET_UNROUTABLE || network == NET_INTERNAL)
            continue;
        proxyType proxy;
        UniValue obj(UniValue::VOBJ);
        GetProxy(network, proxy);
        obj.pushKV("name", GetNetworkName(network));
        obj.pushKV("limited", !IsReachable(network));
        obj.pushKV("reachable", IsReachable(network));
        obj.pushKV("proxy", proxy.IsValid() ? proxy.proxy.ToStringIPPort() : std::string());
        obj.pushKV("proxy_randomize_credentials", proxy.randomize_credentials);
        networks.push_back(obj);
    }
    return networks;
}
static UniValue getnetworkinfo(const JSONRPCRequest& request)