keen: rename some files

games/keen/Makefile

@@ -62,7 +62,7 @@ KEEN_LEVEL1:	keen_level1.o
 
 keen_level1.o:	keen_level1.s zp.inc hardware.inc \
 	print_help.s gr_fast_clear.s quit_yn.s text_drawbox.s \
-	enemies_level1.s item_level1.s \
+	level1_enemies.s level1_items.s \
 	graphics/keen_graphics.inc sprites/keen_sprites.inc \
 	maps/level1_map.lzsa \
 	status_bar.s draw_keen.s move_keen.s gr_putsprite_crop.s \

games/keen/keen_level1.s

@@ -205,8 +205,8 @@ level1_bg_zx02:
 	.include	"move_keen.s"
 	.include	"handle_laser.s"
 	.include	"draw_tilemap.s"
-	.include	"enemies_level1.s"
-	.include	"item_level1.s"
+	.include	"level1_enemies.s"
+	.include	"level1_items.s"
 
 	.include	"level1_sfx.s"
 	.include	"longer_sound.s"