Refactor asset loading

src/asset/asset.h

@@ -26,6 +26,12 @@ static const char_t *ASSET_SEARCH_PATHS[] = {
   NULL
 };
 
+#pragma pack(push, 1)
+typedef struct {
+  char_t header[3];
+} assetheader_t;
+#pragma pack(pop)
+
 typedef struct {
   zip_t *zip;
   char_t systemPath[FILENAME_MAX];