Awkward

Fixed an edge case in `ak.cartesian`. PR 794.

Added a mechanism to cast objects `__array_ufunc__` for scikit-hep/vector. PR 796.

Fixed a subtle bug with lazy RecordArray carrying and parameters: PR 789.

Added 'np.nan_to_num' and 'np.isclose' for Vector: PR 790.

reikdas added a parser to read type strings into type objects. Although this has many uses, its motivation is to construct types for TypedArrayBuilder. PRs 668, 773.

ianna added steps toward the development of a TypedArrayBuilder, though it's not done yet. PRs 690, 767, 781.

trickarcher is developing autograd for elementwise operations in JAX. The main issue is to handle slices in the JAX-compiled or JAX-differentiated code block. PRs 765, 779.

henryiii and pre-commit-ci are improving the development environment. PRs 785, 786.

jpivarski has been fixing bugs. PRs 762, 764, 766, 772, 776, 5999fbd, 784. The last of these, 787, is especially important because it prevents Awkward Array from _breaking_ other Numba extensions!

Fixed `ak.unflatten` to include trailing `0` in its `counts` (in the structure on the left, if `axis != 0` or partitioned, at all otherwise): PR 743.

Implemented `row_groups` parameter of `ak.from_parquet`: PR 748.

Added methods: `ak.Array.to_list`, `ak.Record.to_list` (synonym for `tolist`), and `ak.Array.to_numpy`: PR 750.

NumPy scalars iterated over as numbers: PR 751.

Better error message for bad concatenation: PR 752.

Fixed `ak.num` on PartitionedArrays: PR 757.

drahnreb fixed several issues with categorical arrays and Arrow conversion: PR 727.

jpivarski updated `ak.unflatten` to have an `axis` parameter (PR 731), and to make it work on PartitionedArrays (732), added `ak.run_lengths` (733) and `ak.strings_astype` (734), and implemented `ak.argsort` for strings, fixing some issues with `ak.sort` for strings (736).

Significantly, the depth of arrays was changed to not count the inner dimension of strings: PR 736. Now an unnested array of strings has the same depth as an unnested array of integers: the dimension of the lists comprising the strings themselves doesn't count.

The fix that motivates this patch release is henryiii's repair of the SDist distribution: PR 720. The addition of dlpack wasn't included in the source distribution, so `pip install awkward` without an available wheel was failing due to not having all the headers it needed to compile.

Also fixed jagged slices: issue 723, PRs 725 and 729, as well as a segfault in `ak.flatten`: issue 724, PR 726.