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
case Type::STR: {
        return "\"" + m_name + "\"";
    }
    case Type::NUM:
    case Type::RANGE:
    case Type::AMOUNT:
    case Type::BOOL: {
        return m_name;
    }
    case Type::OBJ:
    case Type::OBJ_USER_KEYS: {
        const std::string res = Join(m_inner, ",", [&](const RPCArg& i) { return i.ToStringObj(oneline); });
        if (m_type == Type::OBJ) {
            return "{" + res + "}";
        } else {
            return "{" + res + ",...}";
        }
    }
    case Type::ARR: {
        std::string res;
        for (const auto& i : m_inner) {
            res += i.ToString(oneline) + ",";
        }
        return "[" + res + "...]";
    }
        
    }
    assert(false);
}
static std::pair<int64_t, int64_t> ParseRange(const UniValue& value)