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
{
        UniValue obj(UniValue::VOBJ);
        obj.pushKV("isscript", false);
        obj.pushKV("iswitness", true);
        obj.pushKV("witness_version", 0);
        obj.pushKV("witness_program", HexStr(id.begin(), id.end()));
        return obj;
    }
    UniValue operator()(const WitnessV0ScriptHash& id) const
    {
        UniValue obj(UniValue::VOBJ);
        obj.pushKV("isscript", true);
        obj.pushKV("iswitness", true);
        obj.pushKV("witness_version", 0);
        obj.pushKV("witness_program", HexStr(id.begin(), id.end()));
        return obj;
    }
    UniValue operator()(const WitnessUnknown& id) const
    {
        UniValue obj(UniValue::VOBJ);
        obj.pushKV("iswitness", true);
        obj.pushKV("witness_version", (int)id.version);
        obj.pushKV("witness_program", HexStr(id.program, id.program + id.length));
        return obj;
    }
};
UniValue DescribeAddress(const CTxDestination& dest)