Maxwell's puzzling demon: Maxwell's puzzling demon v1.5.23

Levels update Added 0-J. Changed entering 9-O, entering 0-ι₂ and A-20. Slightly changed 9-24, 0-16, 0-ν and 0-ξ. Fixed 0-15?₅ and entering 0-20 to prevent unintended solutions. Adjusted the difficulty of 4-9?, 0-16?, 0-…