- feat: lazy-loading and improved caching strategy for hierarchy
child datasets via `RTDC_Hierarchy` (the call to `apply_filter`
is now mandatory for all changes to propagate to the children)
- feat: introduce `RTDC_Hierarchy.rejuvenate`, an alias for
`apply_filter` which more accurately describes what happens there
- feat: added file_monitoring_lru_cache convenience decorator
- enh: new feature bg_med: Median frame background brightness
- enh: add min/max/mean values as scalar dataset attributes (175)