libevent seems to have invaded `libbitcoin_common` via `url.cpp`

`url.cpp` is used only from `test/fuzz/string.cpp` and `wallet/rpcwallet.cpp`

libevent should only be required for bitcoind, bitcoin-cli and (due only to the hack of passing wallet names) bitcoin-qt

else
        {
            strUsage += "\nUsage:  bitcoind [options]                     Start " PACKAGE_NAME "\n";
            strUsage += "\n" + gArgs.GetHelpMessage();
        }
        tfm::format(std::cout, "%s", strUsage);
        return true;
    }
    try
    {
        if (!CheckDataDirOption()) {
            return InitError(strprintf("Specified data directory \"%s\" does not exist.\n", gArgs.GetArg("-datadir", "")));
        }
        if (!gArgs.ReadConfigFiles(error, true)) {
            return InitError(strprintf("Error reading configuration file: %s\n", error));
        }
        
        try {
            SelectParams(gArgs.GetChainName());
        } catch (const std::exception& e) {
            return InitError(strprintf("%s\n", e.what()));
        }
        
        for (int i = 1; i < argc; i++) {
            if (!IsSwitchChar(argv[i][0])) {
                return InitError(strprintf("Command line contains unexpected token '%s', see bitcoind -h for a list of options.\n", argv[i]));
            }
        }
        
        gArgs.SoftSetBoolArg("-server", true);