Suggestion: consider exposing the Uxx and XCore traits for SPSC queues #115
Description
It is currently not possible to be generic over the index type or single core/multi core SPSC queue variants because the traits Uxx and XCore can't be declared as type parameters because they are private.
If the traits were sealed so that the crate retained control over what types could implement Uxx and XCore it would be possible to write more generic code utilizing SPSC queues.