Consider renaming StatusEffect -> StatusEffectType, StatusEffectInstance -> StatusEffect

[supersaiyansubtlety]

1. similar to EntityType+Entity

2. I think it makes more sense to use the StatusEffect name for the thing more closely tied to what you see/experience in game (banner with timer/results of the effect for the duration)

3. I think use of the word Instance should be avoided because it's [redundant+could cause confusion] with instantiation in OOP (except for singleton constants that are just INSTANCE).