4.3.12.1: hotfix for AGP problem that caused random exceptions (#511)
4.3.12:
- [CalDAV] fix StackOverflowError when timezone definitions refer to time zones themselves
- [CalDAV] fix reminder type of default event reminders
- [WebDAV] less strict MIME type processing to increase compatibility
- [Nextcloud] always append /remote.php/dav so that it also works without well-known URLs
- other minor bug fixes and improvements (including further rewriting to Compose)