void lodepng_info_swap(LodePNGInfo* a, LodePNGInfo* b)
{
  LodePNGInfo temp = *a;
  *a = *b;
  *b = temp;
}
void lodepng_info_swap(LodePNGInfo* a, LodePNGInfo* b)
{
  LodePNGInfo temp = *a;
  *a = *b;
  *b = temp;
}