sdl_effect: Implement EFFECT_PAN_IN_* and EFFECT_SKIP_LINE_*

This also fixes incorrect behavior of `CD 1` and `CD 2`.

src/effect.h

@@ -22,6 +22,10 @@
 
 // Effect types of the CE/CD command.
 enum nact_effect {
+	NACT_EFFECT_PAN_IN_DOWN       = 1,
+	NACT_EFFECT_PAN_IN_UP         = 2,
+	NACT_EFFECT_SKIP_LINE_UP_DOWN = 3,
+	NACT_EFFECT_SKIP_LINE_LR_RL   = 4,
 	NACT_EFFECT_WIPE_IN           = 7,
 	NACT_EFFECT_WIPE_OUT          = 8,
 	NACT_EFFECT_ZOOM_IN           = 10,
@@ -124,6 +128,10 @@ enum sdl_effect_type {
 	EFFECT_DITHERING_FADEIN,
 	EFFECT_DITHERING_WHITEOUT,
 	EFFECT_DITHERING_WHITEIN,
+	EFFECT_PAN_IN_DOWN,
+	EFFECT_PAN_IN_UP,
+	EFFECT_SKIP_LINE_UP_DOWN,
+	EFFECT_SKIP_LINE_LR_RL,
 	EFFECT_WIPE_IN,
 	EFFECT_WIPE_OUT,
 	EFFECT_WIPE_LR,