Different wallets may be used for different purposes.  When a notification is triggered, we get the TXID but don't know which wallet is involved.  It would be useful to have different walletnotify actions depending on which wallet is involved by the transaction.

It could be used like (bitcoin.conf):

`walletnotify.walletname=action %s`

Or maybe a more simple and flexible (dynamic-wallets compatible) way:

`walletnotify=action %s %w`

where %w is the name of the wallet.  This way, notify action (and not Bitcoin Core) is responsible for choosing the right action depending on the wallet and it is easier to RPC query the good wallet (ie gettransaction).

* @return the formatted string
 */
std::string HelpMessageGroup(const std::string& message);
/**
 * Format a string to be used as option description in help messages
 *
 * @param option Option message (e.g. "-rpcuser=<user>")
 * @param message Option description (e.g. "Username for JSON-RPC connections")
 * @return the formatted string
 */
std::string HelpMessageOpt(const std::string& option, const std::string& message);
/**
 * Return the number of cores available on the current system.
 * @note This does count virtual cores, such as those provided by HyperThreading.
 */
int GetNumCores();
/**
 * .. and a wrapper that just calls func once
 */
template <typename Callable> void TraceThread(const char* name,  Callable func)
{
    util::ThreadRename(name);
    try
    {
        LogPrintf("%s thread start\n", name);
        func();
        LogPrintf("%s thread exit\n", name);
    }
    catch (const boost::thread_interrupted&)
    {