URGENT: Add owlcat as dependency - with flagmanager compatible FLAG/FLAG_ROW backups prior to flagging

[bennahugo]

REALLY need this functionality to add a flag backup prior to flagging:
ratt-ru/owlcat#81

All CASA tasks that screw with flags have this functionality and neither tricolour nor aoflagger has this capacity. This is a urgent feature request which I will allocate to myself once the owlcat release goes out - a simple shell call will solve very many headaches in the future.

[IanHeywood]

Excellent plan, but please make it optional! Cheers.

[sjperkins]

I suggest doing this with dask if possible. I'm concerned about having to support software with old dependencies. I'm fairly certain this has been done elsewhere. @o-smirnov @JSKenyon @landmanbester?

[o-smirnov]

The owlcat way is not very efficient, either. Flagmanager is a lot snappier, presumably because it allocates boolean columns which use 1-bit storage in casacasore tables? Can we reverse-engineer what it does? I suspect it would be a trivial thing to do with dask...

[sjperkins]

I'm certain someones gone through this exercise before. Pinging @Athanaseus?

[sjperkins]

@SpheMakh, did we work on redoing the owlcat flagging routines in dask? been a while...