message: [RPC] Show the configured/set txfee in getwalletinfo
  Simple consistency addition. This mimmics the output from `getinfo`.
diff: @@ -2128,6 +2128,7 @@ UniValue getwalletinfo(const UniValue& params, bool fHelp)
  " \"keypoololdest\": xxxxxx, (numeric) the timestamp (seconds since GMT epoch) of the oldest pre-generated key in the key pool\n"
  " \"keypoolsize\": xxxx, (numeric) how many new keys are pre-generated\n"
  " \"unlocked_until\": ttt, (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
  + " \"paytxfee\": x.xxxx, (numeric) the transaction fee configuration, set in PIV/kB\n"
  "}\n"
  "\nExamples:\n" +
  @@ -2143,6 +2144,7 @@ UniValue getwalletinfo(const UniValue& params, bool fHelp)
  obj.push_back(Pair("keypoolsize", (int)pwalletMain->GetKeyPoolSize()));
  if (pwalletMain->IsCrypted())
  obj.push_back(Pair("unlocked_until", nWalletUnlockTime));
  + obj.push_back(Pair("paytxfee", ValueFromAmount(payTxFee.GetFeePerK())));
  return obj;
  }
  