This implements a basic CalDav UI, titled "Calendar". It allows creating new calendars and events with a start and end date, URL, location, and description.
You can also import and export ICS (VCALENDAR + VEVENT) files.
It allows editing the ICS directly, for power users.
Additionally, you can hide/display events from certain calendars, change their names and their colors. If there's no calendar created yet in your CalDav server (first-time setup), it'll automatically create one, titled "Calendar".
You can also change the display timezone for the calendar from the settings.
Finally, there's some minor documentation fixes and some other minor tweaks.
Closes#56Closes#89
