Libyang

The complete API/ABI diff to the previous release is available at [netopeer.liberouter.org](https://netopeer.liberouter.org/doc/libyang/abidiff/0.11.112-0.12.112.html).

The main features of this release are:
- various bugfixes
- support for YANG extensions (libyang's schema tree structures changed)
- ietf-metadata implemented - support for annotations represented in data as data nodes' attributes
- added possibility to set all the imported modules as implemented
- YANG parser's error messages extended by the path of the invalid node
- nodes, used in `must` and `when` XPath expressions, which are not found in schema are reported as warnings, not errors - refering non-exiting nodes is generally allowed despite it is useless

The main features of this release are:
- various bugfixes
- include subdirectories of `search path` when looking for the imported modules and included submodules
- NACM extension instances are not printed in schemas - this is a temporary change until the full support of YANG extensions is implemented
- corrected parsing of `backslash`-ed characters in YANG strings (even in YANG 1.0 modules, the clarification from 1.1 is applied)
- changed return code of `lys_features_enable()` and `lys_features_disable()` when the feature is already in the desired state
- improved printing of canonical data values
- improved printing of anydata/anyxml trees

The complete API/ABI diff to the previous release is available at [netopeer.liberouter.org](https://netopeer.liberouter.org/doc/libyang/abidiff/0.10.204-0.11.44.html).

The main features of this release are:
- feature rich YANG utility installed with libyang - `yanglint(1)`
- ability to remove schema(s) from the context (`ly_ctx_clean()` and `ly_ctx_remove_module()`)
- `lys_path()` to get schema path of the specific node
- improved data type resolving according to the leaf/leaf-list value (publicly available via `lyd_leaf_type()`)
- improved logging (printing some of the previously hidden messages)