[ewsdatetime] Support defensive comparisons in EWSTimeZone.__eq__ (#561)
[ewsdatetime] Support defensive comparisons in EWSTimeZone.__eq__ (#561)

* [ewsdatetime] Support defensive comparisons in EWSTimeZone.__eq__

Do not assume other is also an EWSTimeZone instance.

Signed-off-by: Earl Chew <408aef5abfefb2ec478aaf6aa6535a7cc1b91eef@yahoo.com>

* [ewsdatetime] Use self.__class__ to facilitate subclassing

Signed-off-by: Earl Chew <408aef5abfefb2ec478aaf6aa6535a7cc1b91eef@yahoo.com>

ecederstrand/exchangelib