Release 0.2.1 (#27)

* Bump version to 0.2.1

* Simplify readme.

Refactor B-Spline implementation: merge two implementations into one (#…

…14)

* Refactor B-Spline implementation: renamed BSplineCurve and BSplineEmbeddings to BSpline, updated function calls in tests and modules, and optimized gradient computation in _bspline.py. This unifies the B-Spline layer to handle backpropagation more efficiently.

* Fix unit tests to use new class name.

* Refactor: Replace `BSpline` with `BSplineCurveBase` across modules, tests, and documentation, removing redundant `_forward_core` implementation.

* added pre-commit hook installation to the makefile

* Refactor: Rename `BSplineCurveBase` to `BSplineCurve` and `bspline` to `bspline_curves` across modules, tests, benchmarks, and documentation for consistency.

* Update docs.

* Fix: Replace `torch.addcmul` deprecated call with the new calling convention.

* Reran notebooks with the new implementations to verify everything works.

* Refactor: Replace `BSplineEmbeddings` with `BSplineCurve` in `README.md` for consistency with recent renaming

* Fix: Update type hints in `backward` method to support `None` return annotations

* Update: Simplify docstring for `BSplineCurve` module by removing redundant "Base" descriptor

* Fix: Update `backward` method's type hints to use `Optional` to support older python versions.

Merge pull request #11 from alexshtf/readme_doc_clarification

Update README.md with docs clarification