Polliwog

- Add `polliwog.segment.is_point_on_line_segment()`
- `Polyline.sliced_at_points()`: Avoid inserting degenerate segments

- Support NumPy 1.24+

- Allow any version of numpy
- Test in Python 3.9

- Polyline:
- Fix bug in `nearest()` so that `ret_distances` and `ret_t_values` work as intended

- Polyline:
- Add `aligned_along_subsegment()`
- Add optional parameters to `nearest()`
- `ret_distances`
- `ret_t_values`
- `polliwog.polyline.closest_point_of_line_segment()`: Add `ret_t_values`

- CompositeTransform: Pass through `treat_input_as_vector` kwarg.