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().

#include <stdio.h>
#include "openalbridge.h"

int main (int argc, int **argv) {

    openal_init();

    openal_close();

    return 0;
}