Adding actions for opening, flushing, and closing the logs

[emily-howell]

This currently only adds some simple actions for opening, flushing, and closing the logs. I wonder if it would be useful to also add an action for modifying the logging threshold?

[cyrush]

this looks great!

Can you add a note to the CHANGELOG.md file about these actions and a short section in the docs?

We can think about the mpi relevant options rank, etc in the future.

We could also add support for log_threshold to open_log so folks can use one action to setup everything up.

The separate actions for log and echo thresholds are a good addition.

[emily-howell]

Yes, I can add a note to the change log.

I have a draft of the MPI relevant options but I don't have tests written for it yet so I didn't push them.

I like the idea of adding the log threshold to the options for open_log. That should be a quick change so I will add that too.

[emily-howell]

@cyrush I circled back to this and updated the MPI thresholding to be Debug for rank 0 and Warnings for all other ranks. Does that work?

[cyrush]

@emily-howell sounds good, thanks!

[cyrush]

Merging, thanks again for this!