Version 2.15.3
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- Properly sort image filenames containing numbers (Felix Riemann) [#340957]
- Thumbnailing fixes (Felix Riemann) [#342817]
- Fix printing for images with alpha channel (Jan Kümmel) [#322057]
- Updated translations: Ignacio Casal Quinteiro (gl), Ankit Patel (gu), 
  Theppitak Karoonboonyanan (th), Clytie Siddall (vi), Inaki Larrañaga (eu), 
  Pema Geyleg (dz), Francisco Javier F. Serrador (es)