Add --note flag to associate messages with frames

[joelostblom]

@jmaupetit This is a continuation of #337. As mentioned there, I merged master into this branch because the rebase was a headache with so many conflicting changes (possible I'm not doing this optimally). I suspect this doesn't matter since you usually squash when merging, but it would be great if this was given priority over other PR's, since it is hard to rebase if master is updated.

I added @k4nar 's suggestions in the three first commits. Just a comment that although the plural form --notes is more natural for log since it is short for short_notes, it might be confusing since it is --note everywhere else. I'll let you decide what to do, if anything.

I added three commits of my own, only 4e0e4b6 is a functional change. Without it, I would not be able to edit frames since the new note field would be interpreted as the updated_at field and watson edit raised an error trying to convert this to a date. I have added this and a few more comments on the code also.

Close #337 #252 #93

[joelostblom]

@k4nar Just a reminder to have a look at this when you get a chance.

[joelostblom]

@k4nar and @jmaupetit I have been running this branch locally since opening the PR and it seems to be working well (although I don't use notes that often tbh). Just a reminder to review this PR when you have time.

[joelostblom]

Just a note that I didn't use this feature much and I am no longer running this branch locally. I ran into some issues with my frames file format when I moved it to a new watson installed from the main branch, so I went ahead and deleted the notes fields for each frame and it is now working again. I didn't have time to investigate exactly why this issue occurred, but thought I would leave a note that there might be incompatibilities with newer watson versions in case others are considering running from this PR (you probably should wait until when/if this feature is merged into main).