0.5.0

Breaking Changes

• invocation.priority removed; use invocation.context[priority] instead.
• Invocation.Submitted.priority replaced with context.
• Serialized invocations from previous versions are incompatible.

Added

• QueueVar for user-defined serializable context variables that propagate across queue boundaries.
• QueueContext mapping to access captured context on invocations.
• priority is now a QueueVar instance (same context manager syntax as before).