inotify

Change prune option to another with two alternatives: deepscan and lazy? Lazy does not build internal cache, and is kinda like prune=0. Deepscan scans the entire tree and builds internal cache based on this. Use `inotify` to modify cache. Expose changes to fs with this with inotify again out.

[fuser docs](https://docs.rs/fuser/latest/fuser/struct.Notifier.html#method.inval_inode) as well.