Move more of the utility headers into /include/mcaselector-lite.

These headers have no associated C files, and are mainly used for
utility logic.
Having them in `/include` makes them more easily located, and more
globally used.

We are using "classic" header guards here over `#pragma once` for better
support. Since `#pragma once` is defined by the compiler, rather than
standard C.
Why isn't it used across the project? I have no idea.

src/dat/nbt.h

@@ -6,12 +6,12 @@
 #pragma once
 
 #include <assert.h>
-#include <endian.h>
+#include <mcaselector-lite/atrb.h>
+#include <mcaselector-lite/endian.h>
+#include <mcaselector-lite/types.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
-#include "../types.h"
-#include "../util/atrb.h"
 
 /* NBT (named binary tag) is a tree data structure. Tags have a numeric type ID, name and a payload.
  * NBT files are a compressed `compound` tag. GZip is the compression used in most cases,