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 (err_string.length() > 0) {
        return JSONRPCError(RPCErrorFromTransactionError(terr), err_string);
    } else {
        return JSONRPCError(RPCErrorFromTransactionError(terr), TransactionErrorString(terr));
    }
}
/**
 * A pair of strings that can be aligned (through padding) with other Sections
 * later on
 */
struct Section {
    Section(const std::string& left, const std::string& right)