Better filesystem monitoring

[phockett]

Currently implement a basic dir poll, with Glob + dictionary comparisons (as sets).

Lots of options for more sophisticated methods. Should also integrate with proper event queue/trigger routines.

• fswatch (cross platform)
• Watchdog (cross platform) (lots of examples online, e.g. threaded queue example here, and basic demo)
• inotifyx (linux) Python binding for inotify. (Not lots of similar packages/project, e.g. pyinotify, although that seems to be not recommended - although this is old.)
• Qt FileSystemWatcher

[phockett]

During SACLA run Oct. 2021 monitoring of Box dirs was very slow, sometimes several mins for files to be found after appearance. Unclear how much of this was dir watching method, and how much machine and/or Box-specific.