* replace strings by class references
* allow 64 chars for username
* fix time can be optional and null
* fix timezone is not respected
* bump version
* fix br in attribute
* support different visible duration from booked duration
* fix image URL
- setting "rounding days" not required
- developer: added user pref for public holiday group (to be used by plugins)
- developer: added WorkingTimeYearEvent (to be used by plugins)
- user pref: cleanup work contract form and support more fields (to be used by plugins)
- code cleanup
- bump theme and composer packages
