Fix endianness & 64-bit in 3D asset loading code

Combination of plumbing BE(T) through everything, making BE<T> have template specializations, and inverting at load time where more practical.

src/dusk/endian.cpp

@@ -0,0 +1,23 @@
+#include <dolphin/gx.h>
+#include "dusk/endian.h"
+
+template <>
+GXColorS10 BE<GXColorS10>::swap(GXColorS10 val) {
+    return {
+        be16s(val.r),
+        be16s(val.g),
+        be16s(val.b),
+        be16s(val.a),
+    };
+}
+
+#define IMPL_ENUM(type) \
+    template <> \
+    type BE<type>::swap(type val) { \
+        return static_cast<type>(be32(val)); \
+    }
+
+IMPL_ENUM(GXCullMode);
+IMPL_ENUM(GXAttr);
+IMPL_ENUM(GXAttrType);
+IMPL_ENUM(GXCompType);