Built against `master` branch 801dd40666d1e6009920ad3ff755c7bb993b2a62:

If I have no wallet.dat file and run:

    bitcoind -usehd=0

A new wallet.dat file is created and an HD seed is assigned.

I see an error message in the source:

    "Error loading %s: You can't disable HD on an already existing HD wallet or create new non-HD wallets."

but that doesn't get shown because `fFirstRun` is true, and so the code which checks for `-usehd` values doesn't run.

If it's no longer possible to create non-HD wallets, specifying -usehd=0 when creating a wallet should be an error, and not get silently ignored.
* removed from the map during serialization):
     *
     *     "fromaccount"     - serialized strFromAccount value
     *     "n"               - serialized nOrderPos value
     *     "timesmart"       - serialized nTimeSmart value
     *     "spent"           - serialized vfSpent value that existed prior to
     *                         2014 (removed in commit 93a18a3)
     */
    mapValue_t mapValue;
    std::vector<std::pair<std::string, std::string> > vOrderForm;
    unsigned int fTimeReceivedIsTxTime;
    unsigned int nTimeReceived; 
    /**
     * Stable timestamp that never changes, and reflects the order a transaction
     * was added to the wallet. Timestamp is based on the block time for a
     * transaction added as part of a block, or else the time when the
     * transaction was received if it wasn't part of a block, with the timestamp
     * adjusted in both cases so timestamp order matches the order transactions
     * were added to the wallet. More details can be found in
     * CWallet::ComputeTimeSmart().
     */
    unsigned int nTimeSmart;
    /**
     * From me flag is set to 1 for transactions that were created by the wallet
     * on this bitcoin node, and set to 0 for transactions that were created
     * externally and came in through the network or sendrawtransaction RPC.
     */
    char fFromMe;
    std::string strFromAccount;
    int64_t nOrderPos;