Aligned-textgrid

What's Changed
- New `.interleave_class()` method for AlignedTextGrids. You can extend the entry class hierarchy and interleave a new SequenceTier within TextGrids.


**Full Changelog**: https://github.com/Forced-Alignment-and-Vowel-Extraction/alignedTextGrid/compare/v0.5.0...v0.6.0

What's Changed
* `SequenceIntervals` now have a unique id based on their location in the hierarchy.
* A new `to_df()` function that returns a polars data frame for most `aligned_textgrid` objects.

**Full Changelog**: https://github.com/Forced-Alignment-and-Vowel-Extraction/alignedTextGrid/compare/v0.4.1...v0.5.0

What's Changed
* changed default point tier behavior by JoFrhwld in https://github.com/Forced-Alignment-and-Vowel-Extraction/alignedTextGrid/pull/130
* Now `SequencePointTier()` defaults to an empty sequence list.
* implement sequence first last by JoFrhwld in https://github.com/Forced-Alignment-and-Vowel-Extraction/alignedTextGrid/pull/128
* `SequenceInterval`s, `SequenceTier`s and `SequencePointTier`s now all have `.first` and `.last` attributes

**Full Changelog**: https://github.com/Forced-Alignment-and-Vowel-Extraction/alignedTextGrid/compare/v0.4.0...v0.4.1

What's Changed

* New `SequencePoint` and `SequencePointTier` classes, to handle Praat point tiers
* `custom_classes()` can generate custom `SequencePoint` subclasses
* Individual tiers within `TierGroup`s or `PointsGroup`s can now be dot-accessed with the name of the tier's entry class *if* it is unique.

Now, multiple different hierarchies can be included in a single aligned textgrid.

What's Changed

Documentation fixes