Make the notification extension mandatory on Windows

[smunkel]

Right now the non Windows version is mandatory, so this changes that for the windows version. Because the windows version of the notification extension creates an icon in the system tray, this patch also disables the status icon extension for Windows.

[thp]

Merged, thanks: http://gpodder.org/commit/6b87dd77

What happens when the user doesn't have pywintypes or win32gui installed?
Are there cases where the user might want to disable the notification extension?

[smunkel]

It will fail silently (unless you could the log). As for disabling the notifications, Windows itself has the tools to handle notifications and icons for applications so that should be sufficient.

[thp]

Fail silently means that the user doesn't get an error message (except for the log, which is okay), and gPodder still works as if the extension would be disabled, right? If Windows has support for disabling notifications and icons, that's great - nothing left to do there. Thanks again for the patch :)