allow admins to add custom fields to the event form for calendars

[sproctor]

Allow calendars to have additional fields for their events. Such as: number of people attending, location, or whatever else they want.

[lindquist]

This feature could be useful for multilingual calendars as well, you could imagine having separate fields for a few different languages

[amoskarugaba]

I think it would be a cool Idea if Admins had an option for adding more custom fields to the event form