clone() methods returning a supertype

[stephengold]

clone() returns an object of the same type and should be declared accordingly.

The following clone() methods are declared as returning another type of object:

• AudioTrack.clone() returns Track
• CloneableSmartAsset.clone() returns Object
• CompactArray.clone() returns Object
• DefaultParticleInfluencer.clone() returns ParticleInfluencer
• DistanceLodCalculator.clone() returns LodCalculator
• EffectTrack.clone() returns Track
• EmptyParticleInfluencer.clone() returns ParticleInfluencer
• InstancedNode.clone() returns Node
• IrBoneWeightIndex.clone() returns Object
• NewtonianParticleInfluencer.clone() returns ParticleInfluencer
• PerspectiveLodCalculator.clone() returns LodCalculator
• TestAssetCache.DummyData.clone() returns Object