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().
#! /usr/bin/sed -nf
s/^#define *FREETYPE_MAJOR *\([^ ][^ ]*\).*$/freetype_major="\1" ;/p
s/^#define *FREETYPE_MINOR *\([^ ][^ ]*\).*$/freetype_minor=".\1" ;/p
s/^#define *FREETYPE_PATCH *\([^ ][^ ]*\).*$/freetype_patch=".\1" ;/p