Add autolisting

Makefile

@@ -1,8 +1,12 @@
-all: game.tap
+all: game.tap list.txt
+
+list.txt: game.tap
+	listbasic game.tap > list.txt
+	
 game.tap: pac.bas
 	zmakebas -l -i 1 -s 1 -n pac -a 1 -o game.tap pac.bas
 
 clean:
-	rm -f *.tap
+	rm -f *.tap list.txt
 
 .PHONY: all clean