Individual User Schedule Calendar Export

[ChrisBr]

It would be a greate feature if a users can create their own schedule.
E.g. they can mark events and then they will get an individual schedule with the events they want to attend
This is related to #18 (can maybe combined to one GSoC project?)

[althio]

I would love this feature.
I think it is a very-very-nice-to-have for bigger events, and I am a big struggling right now with the global schedule here (12 tracks...)

Alternatively or additionally, I would like to export the generated schedule or each separate sessions to a calendar (see #433 (comment)).

[differentreality]

For the record the user schedule is being implemented by @Ana06 in #1142 and should be ready soon.

Let's keep/edit this issue for calendar export of the user schedule.