Added 0.2, pre-alpha finished, now is alpha; added <sound> and <music>
for <game>, <bullet>, <enemy> and <wave>; added attributes "power" to
<bullet>, "respawn-time" to <player>, "lifes" to <player>, "points" to
<enemy> and "layer" to <sprite-label> and <text-label>; added score
system and counter, player's bullets now damage the enemy and lots of
bug fixes. Also added a lot of SFX content from Touhou.