Undo PokeCodec's PRs

This commit undoes most of PokeCodec's PRs after the debate in chat. Some
harmless or completely superseded PRs have been left alone, as there is not
much benefit in attempting to undo them.

Reverts #1104, #1108, #1115, #1118, #1119, #1124, #1126, #1127, #1132, #1136,
#1137, #1139, #1140, #1144, #1148, #1149, #1150, #1153, #1155, #1177, #1179,
#1180, #1181, #1182 and #1183.

src/confetti_util.c

@@ -30,8 +30,10 @@ static void sub_81520A8(void *dest, u16 value, u8 left, u8 top, u8 width, u8 hei
 
 static void sub_8152134(void *dest, const u16 *src, u8 left, u8 top, u8 width, u8 height) // Unused.
 {
-    u8 i, j;
-    u8 x, y;
+    u8 i;
+    u8 j;
+    u8 x;
+    u8 y;
     const u16 *_src;
 
     for (i = 0, _src = src, y = top; i < height; i++)