Docs and example code: use the icalendar .new method

[tobixen]

The calendar.save_object can generate valid icalendar code, actually working as a "friendly frontend" to the icalendar library. However, as of collective/icalendar#879 (expected to be released in icalendar 7.0.0) icalendar comes with built-in-"friendliness"

Example code and doc should be rewritten according to the pattern suggested in collective/icalendar#857 (comment)

(My code should by now be redundant, and should gradually be deprecated and removed ... but that should be split out as a separate issue)

[SashankBhamidi]

Thanks for the mention @tobixen!

Glad PR #879 can help eliminate the need for workaround code. Happy to assist with the transition to the new API if needed.

[tobixen]

I have some test code now that breaks. Oh well. (and this is an edited message, the message I originally posted here was posted to the wrong issue).

[tobixen]

Of course this depends on icalendar7 being released.