Piargus

- Add alias `Node` for `TreeHierarchyNode`.
- Make `SafetyRule` directly available.
- `TreeHierarchy` is now backed by [littletree](https://github.com/lverweijen/littletree).

- Add `TreeHierarchie.create_node` and `get_node` for making node retrieval easier.

- Rename `CodeHierarchy` to `LevelHierarchy`.
- Move attribute `total_code` of `InputData` to `Hierarchy`.
- Add `FlatHierarchy`, which is the same as setting no hierarchy.
- Add `linked_suppress_method` to Job for protecting tables which are linked.

- Rename `Hierarchy` to `TreeHierarchy`.
- Rename `GraphRecode` to `TreeRecode`.
- Add `CodeHierarchy` as an alternative to TreeHierarchy.
- Refactor TreeHierarchy.
The implementation is now backed by anytree.
Individual nodes can be accessed by `get_node()`.
- Hierarchy now keeps track of `indent` itself. This parameter no longer needs to be supplied to `to_hrc`.
- Replace methods `to_dataframe` and `from_dataframe` by `to_rows` and `from_rows`.
- `<TOTCODE>` is now always written to metadata.

- Add support for recode table (requires TauArgus version >= 4.2.4).
- Make `name` parameter on most objects obsolete, except Job.
- Remove obsolete parameter `safety_rules_holding`.
Parameter `safety_rule` is very flexible and can be passed a dict.
- Improve the methods of `BatchWriter` to accept both strings and objects.
- Tables can now be passed to Job as both iterable or dict.
Tables will now be stored in a TableSet object.
- Experimental linked protection is possible when using a TableSet.
Although it seems to produce output, this feature is not documented in the Tau Argus manual.
Therefore, usage cannot be recommended (a warning will be shown).