[PORTAL BETA] intro_lvl5a with commentary

This is the level that later became test chamber 10 in the final game. You may notice that this one immediately follows chamber 08. That is because it appears that chamber 09 did not appear in the game during its Prospekt era of development, there is nothing inside that chamber's map file to imply that it would have been in it. In either case, please let me know what you think.