prepare for v1.4.0 release

[jswhit]

cftime.datetime now no longer uses calendar-specific sub-classes. Legacy functions (including calendar-specific subclasses) now kept in a separate file (_cftime_legacy.pyx).

[jswhit]

@spencerkclark - would you mind running the xarray tests again on this branch before I make a release? I decided to remove the calendar-specific sub-classes from cftime.datetime and I want to make sure that doesn't break anything. (datetime.__add__, datetime.__sub__ and num2date used to return the calendar specific sub-classes)

[spencerkclark]

That's nice, and it looks like you kept the ability to import the calendar-specific sub-classes, which we do still use in the xarray tests (we can probably migrate away from that at some point). I ran the tests with this branch and everything passed.

[jswhit]

thanks @spencerkclark. merging now.

[spencerkclark]

That's nice, and it looks like you kept the ability to import the calendar-specific sub-classes, which we do still use in the xarray tests (we can probably migrate away from that at some point). I ran the tests with this branch and everything passed.

@jswhit unfortunately I think the fact that the xarray test suite uses the legacy types prevented it from catching some (fairly serious) errors that arose when using the new universal cftime.datetime objects. Perhaps making that change was a bit premature after all. Would you be open to reverting that change and issuing a patch release? Since this was my mistake, I'd be happy to take on the work of writing the PR to revert those additional changes.

[spencerkclark]

xref: pydata/xarray#4853

[spencerkclark]

@jswhit many thanks for issuing the 1.4.1 release! I missed it a few days ago because it did not show up in the "Releases" section on the GitHub repo homepage.

Is there a way to update that too?