### 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

"\nArguments:\n"
            "1. nrequired        (numeric, required) The number of required signatures out of the n keys or addresses.\n"
            "2. \"keys\"         (string, required) A json array of bitcoin addresses or hex-encoded public keys\n"
            "     [\n"
            "       \"address\"  (string) bitcoin address or hex-encoded public key\n"
            "       ...,\n"
            "     ]\n"
            "3. \"account\"      (string, optional) DEPRECATED. An account to assign the addresses to.\n"
            "\nResult:\n"
            "\"address\"         (string) A bitcoin address associated with the keys.\n"
            "\nExamples:\n"
            "\nAdd a multisig address from 2 addresses\n"
            + HelpExampleCli("addmultisigaddress", "2 \"[\\\"16sSauSf5pF2UkUwvKGq4qjNRzBZYqgEL5\\\",\\\"171sgjn4YtPu27adkKGrdDwzRTxnRkBfKV\\\"]\"") +
            "\nAs json rpc call\n"
            + HelpExampleRpc("addmultisigaddress", "2, \"[\\\"16sSauSf5pF2UkUwvKGq4qjNRzBZYqgEL5\\\",\\\"171sgjn4YtPu27adkKGrdDwzRTxnRkBfKV\\\"]\"")
        ;
        throw std::runtime_error(msg);
    }
    LOCK2(cs_main, pwallet->cs_wallet);
    std::string strAccount;
    if (!request.params[2].isNull())
        strAccount = AccountFromValue(request.params[2]);
    
    CScript inner = _createmultisig_redeemScript(pwallet, request.params);
    CScriptID innerID(inner);
    pwallet->AddCScript(inner);
    pwallet->SetAddressBook(innerID, strAccount, "send");
    return EncodeDestination(innerID);
}
class Witnessifier : public boost::static_visitor<bool>