When downloading and running Bitcoin core for the first time, after clicking through the "Are you sure you want to open. it?" screen, there's a possibility that macOS will pass an argument like `-psn_0_SOME_ID` to the application, which results in a shutdown as it's an invalid argument:

![v0 19 0rc1 args shutdown](https://user-images.githubusercontent.com/863730/67034964-b026fc00-f0e6-11e9-8462-70d0fcf613e6.png)

This only happens on the first run, subsequent opens will work fine, but we should filter these out, otherwise it's a poor and confusing first experience.

key[0] = '-';
#endif
        if (key[0] != '-')
            break;
        
        if (key.length() > 1 && key[1] == '-')
            key.erase(0, 1);
        const unsigned int flags = FlagsOfKnownArg(key);
        if (flags) {
            if (!InterpretOption(key, val, flags, m_override_args, error)) {
                return false;
            }
        } else {
            error = strprintf("Invalid parameter %s", key.c_str());
            return false;
        }
    }
    
    auto it = m_override_args.find("-includeconf");
    if (it != m_override_args.end()) {
        if (it->second.size() > 0) {
            for (const auto& ic : it->second) {
                error += "-includeconf cannot be used from commandline; -includeconf=" + ic + "\n";
            }
            return false;
        }
    }
    return true;
}
unsigned int ArgsManager::FlagsOfKnownArg(const std::string& key) const