Add `agendaupdate` subcommand

[michaelmhoffman]

Add the agendaupdate subcommand, the minimum viable product for #550.

Refactor gcalcli.gcal.GoogleCalendarInterface._tsv(), replacing the long list of if statements with a modular design using a series of gcalcli.details.Handler classes.

My plan is to keep making additions to the michaelmhoffman/issue-550 branch, pushing from my local machine when I have changes that implement each of the checklist items in #550. I test locally with Python 3.5-Python 3.8. Please feel free to review and apply now or when I'm done with the whole set.

[michaelmhoffman]

@jcrowgey This pull request fully implements #550, passes the tox tests, and is ready for review.

[insanum]

@michaelmhoffman would you be interested in helping us mange the gcalcli project and have commit access? Your contributions have been meaningful and I'm sure you can help guide gcalcli in the right direction.

[michaelmhoffman]

I'm happy to help when I can but I just had a new baby so probably can't dedicate much time. Will probably keep making contributions either way.

On Wed, Sep 30, 2020, 2:03 PM Eric Davis notifications@github.com wrote:

@michaelmhoffman https://github.com/michaelmhoffman would you be interested in helping us mange the gcalcli project and have commit access? Your contributions have been meaningful and I'm sure you can help guide gcalcli in the right direction.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/insanum/gcalcli/pull/553#issuecomment-701551553, or unsubscribe https://github.com/notifications/unsubscribe-auth/ADJLS255WGO4THLVYL5R7YLSINXHBANCNFSM4PSZGGNA .

[michaelmhoffman]

Should I use a merge commit, squash and merge, or rebase and merge?

[michaelmhoffman]

Looks like squash was what was used before.