Patched memory leak (closes #217)

source/loading.c

@@ -540,8 +540,12 @@ bool load_preview_from_buffer(void * buf, u32 size, C2D_Image * preview_image, i
 
             memcpy(preview_image->tex->data + dst, px, sizeof(u32));
         }
+
+        free(row_pointers[j]);
     }
 
+    free(row_pointers);
+
     *preview_offset = (width-400)/2;
 
     return true;