Summary: Some few workarounds to support yet more different calendar servers and cloud providers, some few minor enhancements needed by various contributors, and some minor bugfixes.
Added
* Support for very big events, credits to github user aaujon in https://github.com/python-caldav/caldav/pull/301
* Custom HTTP headers was added in v1.2, but documentation and unit test is added in v1.3, credits to github user JasonSanDiego in https://github.com/python-caldav/caldav/pull/306
* More test code in https://github.com/python-caldav/caldav/pull/308
* Add props parameter to search function, credits to github user ge-lem in https://github.com/python-caldav/caldav/pull/315
* Set an id field in calendar objects when populated through `CalendarSet.calendars()`, credits to github user shikasta-net in https://github.com/python-caldav/caldav/pull/314
* `get_relatives`-method, https://github.com/python-caldav/caldav/pull/294
* `get_dtend`-method
Fixed
* Bugfix in error handling, credits to github user aaujon in https://github.com/python-caldav/caldav/pull/299
* Various minor bugfixes in https://github.com/python-caldav/caldav/pull/307
* Compatibility workaround for unknown caldav server in https://github.com/python-caldav/caldav/pull/303
* Google compatibility workaround, credits to github user flozz in https://github.com/python-caldav/caldav/pull/312
* Documentation typos, credits to github user FluxxCode in https://github.com/python-caldav/caldav/pull/317
* Improved support for cloud provider gmx.de in https://github.com/python-caldav/caldav/pull/318
Changes
* Refactored relation handling in `set_due`