* [ENH] run calendar event CRUD operations through Caldav server to support scheduling, notifications, iTip and other goodies; build Caldav client to use locally in Tiki code itself to communicate with the local server
* [ENH] support custom Tiki calendar event attributes in caldav backend, support recurring event CRUD operations, custom event overrides and other missing elements in caldav integration
* [ENH] caldav property storage in Tiki to enable calendar-availability property on principal's inbox and availability components in free-busy reports
* [FIX] caldav principals backend user search fix
* [ENH] add examples for caldav availability and free-busy reports
* [ENH] caldav availability UI: client to get data from server and list/index page
* [ENH] add basic create/edit UI for availability slots
* [ENH] calendar subscriptions: UI and functionality to subscribe to external calendars
* [ENH] calendar subscription synchronization - automated via system scheduler job and manual via console command - working for both ics exports and remote caldav servers with basic http auth via dsn content sources
* [ENH] calendar subscriptions: show events the same way as normal Tiki calendar items
* [FIX] subscribed calendars: UI updates to edit, show events in preview mode and fix display
* [ENH] recurrence rules management through calendar and availability sections, finish create/edit operations on availability components
* [ENH] caldav free-busy report now includes availability for calendar's owner availability components; add documentation for caldav requests and responses
* [ENH] caldav: free-busy availability report exposed in Tiki UI - when creating calendar events, users can check availability of attendees/invitees for the given time period +/- 1 week
* [ENH] appointment slots, default calendar selection in availability, schedule UI with choice of date and availability slots, auto-populate part of the event fields
* [ENH] appointment slots: display busy and free slots per avaialbility components, allow clicking on free ones and open modal with most calendar item fields prefilled
* [ENH] appointment slots: embedded layout, option to embed on external sites, fix session cookie handling to allow embedding, fix calendar event creation by anoynmous users