### Describe the issue

I added a second new wallet2.dat. Now I wanted to encrypt it, but `bitcoin-cli help` does not show the command to do so, I need to use `bitcoin-cli -rpcwallet=wallet2.dat help`. This is very un-intuitive, and bad for a help function.

### Can you reliably reproduce the issue?

1. have an encrypted default wallet
2. add new multi wallet wallet2.dat via config file or cmd line options
3. naive `bitcoin-cli help` does not show command to encrypt second wallet.

### Expected behaviour

All wallet encryption, lock and unlock commands should be shown unconditionally in `bitcoin-cli help`.

The dynamic hiding of some lines is arguably worse than the benefit with multiple wallets.

### Actual behaviour

`bitcoin-cli help` shows only wallet encryption commands appropriate for the default wallet.

### What version of bitcoin-core are you using?

bitcoind 0.15.0.1~dfsg-1
deb http://ppa.launchpad.net/luke-jr/bitcoin-core-bip148-unofficial-builds/ubuntu zesty main

### Machine specs:
- OS: Debian 9.2

+ HelpExampleRpc("getbalance", "\"*\", 6")
        );
    ObserveSafeMode();
    LOCK2(cs_main, pwallet->cs_wallet);
    const UniValue& account_value = request.params[0];
    const UniValue& minconf = request.params[1];
    const UniValue& include_watchonly = request.params[2];
    if (account_value.isNull()) {
        if (!minconf.isNull()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER,
                "getbalance minconf option is only currently supported if an account is specified");
        }
        if (!include_watchonly.isNull()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER,
                "getbalance include_watchonly option is only currently supported if an account is specified");
        }
        return ValueFromAmount(pwallet->GetBalance());
    }
    const std::string& account_param = account_value.get_str();
    const std::string* account = account_param != "*" ? &account_param : nullptr;
    int nMinDepth = 1;
    if (!minconf.isNull())
        nMinDepth = minconf.get_int();
    isminefilter filter = ISMINE_SPENDABLE;
    if(!include_watchonly.isNull())
        if(include_watchonly.get_bool())
            filter = filter | ISMINE_WATCH_ONLY;
    return ValueFromAmount(pwallet->GetLegacyBalance(filter, nMinDepth, account));
}
UniValue getunconfirmedbalance(const JSONRPCRequest &request)