load map first pass

src/rpg/world/map.h

@@ -13,6 +13,7 @@
 #define MAP_WIDTH_MAX 64
 #define MAP_HEIGHT_MAX 64
 #define MAP_TILE_COUNT_MAX (MAP_WIDTH_MAX * MAP_HEIGHT_MAX)
+#define MAP_LAYER_COUNT_MAX 2
 
 typedef struct {
   uint8_t id;