0.4.2

• Added two AnimationPair constructors to cover all the possible cases: (Animation in, AnimationFX out) and (AnimationFX out, Animation out);
• Added a specific IllegalArgumentException error when passing one or more null values to AnimationPair (from #1);
• Downgraded Kotlin from 1.5.31 to 1.4.31 for compatibility reasons (from #1).