Added strftime to Date

[APCBoston]

Fixes #870
#942 arose during testing but does not appear to be created by/related to this patch (or, for that matter, reproducible)

[APCBoston]

Reopening as this was closed in error.

[nekohayo]

Hi @APCBoston, thank you for looking into this and sorry for the long development cycle we have been through. Apologies for the inconvenience; the new codebase is expected to be much better to work with.

The big refactoring has finally landed (see the pinned 0.7 tracking issue for details)!

It might be good to rebase this to the latest master to facilitate your testing.

[nekohayo]

Actually, this apparently does not conflict with master (much to my surprise), but it would be good to test with this on top of master to be sure that it all works correctly.

[APCBoston]

How exciting that the megaport is done! I'll do the rebase now.

[APCBoston]

Looking at the GH Actions for the repo, it appears that automated unit testing is currently broken? The test failure doesn't appear directly related to the code in this PR.

[nekohayo]

Indeed, see also #999 ;)

[diegogangl]

Sorry for long delay @APCBoston! This LGTM, it doesn't conflict with anything in the megabranch and it adds some functionality to the Date class.
Thanks! Merging