add queue.max_acked_checkpoint and queue.checkpoint_rate settings
now using checkpoint.max_acks, checkpoint.max_writes and checkpoint.max_interval
rename options
wip rework checkpointing
refactored full acked pages handling on acking and recovery
correclty close queue
proper queue open/recovery
checkpoint dump utility
checkpoint on writes
removed debug code and added missing newline
added better comment on contiguous checkpoints
fix spec for new pipeline setting