Previously, even if tiffslide was the chosen backend, openslide would still be used first to get mpp. This could cause panics if a slide could not be read by openslide. This panic could confuse users because they asked to use tiffslide. This commit changes the mpp reading function to use the chosen backend or tifffile if that backend fails.
Previously, even if tiffslide was the chosen backend, openslide would still be used first to get mpp. This could cause panics if a slide could not be read by openslide. This panic could confuse users because they asked to use tiffslide. This commit changes the mpp reading function to use the chosen backend or tifffile if that backend fails.
related to #225