Add onGameTick20 to try and encourage lua to be a bit more efficient. Rewrite Space Invasion to use it. Top speed of aliens is 25% higher now, although that could be changed, I kinda liked it. Change parameter order of div().

/*
 * Copyright (C) 2008 Remko Troncon
 */

#ifndef AUTOUPDATER_H
#define AUTOUPDATER_H

class AutoUpdater
{
    public:
        virtual ~AutoUpdater();

        virtual void checkForUpdates() = 0;
};

#endif