Consider DequeFile

[JakeWharton]

There's not much reason to be solely a queue when behaving like a stack is trivial. We should consider making QueueFile a DequeFile, perhaps with stack-only or queue-only interfaces? Same for the object mapping layer.

Maybe we ship master as is for Tape 2 and then make this Tape 3. Or we could change QueueFile to an interface so that we can add StackFile and DequeFile later.

[oldergod]

It probably has to be Kotlin multiplatform.