Works now:

  * Maintain personal calendar

Pending:

  * Define calendar naming logic
    shared_$GROUP
    public
  * Create shared calendar
  * Publish shared calendar
  * Archive public shared calendar
    + Stop mirroring from CalDAV to iCalendar
    + Copy iCalendar file to archive section
    + Update iCalendar link on public web page
    + Remove iCalendar file at old location
    + Remove CalDAV symlink for all members of sharegroup
    + Remove CalDAV directory for sharegroup owner
  * Document personal calendaring
  * Document shared calendaring