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
#ifndef BITCOIN_RPC_UTIL_H
#define BITCOIN_RPC_UTIL_H
#include <node/transaction.h>
#include <outputtype.h>
#include <pubkey.h>
#include <protocol.h>
#include <rpc/protocol.h>
#include <rpc/request.h>
#include <script/script.h>
#include <script/sign.h>
#include <script/standard.h>
#include <univalue.h>
#include <string>
#include <vector>
#include <boost/variant.hpp>
class FillableSigningProvider;
class CPubKey;
class CScript;
struct InitInterfaces;
extern InitInterfaces* g_rpc_interfaces;
/** Wrapper for UniValue::VType, which includes typeAny:
 * Used to denote don't care type. */
struct UniValueType {
    UniValueType(UniValue::VType _type) : typeAny(false), type(_type) {}