Main changes of this release are:
- new SO version 3
- with some non-backwards compatible changes
- transition manual from version 2 in docs
- (leaf-)list instance semantic ordering
- sorts instances based on their values or their key values
- minor performance cost
- logging API improved
- new parsing flag
LYD_PARSE_STORE_ONLY- avoids value validation
- run-time plugin support
- build improvements
- lots of other bugfixes and optimizations