b: rename "no" variables to "n"
f: convert to slf4j logging & fix log-only errors
F: cannot rely on nanoTime across VM restarts for persisted queue, only use seconds precision anyway
f: convert shutdown hook & thread pool
f: factor out timer-tasks to avoid hard reference from an active thread
f: return type / overly restrictive list type
b: test peek/receive against delete function
v: remove version file