Version 2.0.0rc5

This is one of the last pre-releases before 2.0.0. Most of the focus now is on last-minute API changes; the API can't change without a deprecation cycle after 2.0.0.

New features

• feat: made 'very optional' arguments keyword-only by @jpivarski in #1905
• feat: rename toXXX methods by @agoose77 in #1919
• feat: replace nplike with backend in to_buffers by @agoose77 in #1942
• feat: add rich IPython display hook to array/record by @agoose77 in #1938
• feat: move long-range metadata checks to constructors by @jpivarski in #1939

Bug-fixes and performance

• fix: refactor '_nextcarry-outindex' to have the same signature everywhere by @ioanaif in #1911
• fix: ignore .nox by @ianna in #1912
• refactor!: make Content initialisers take nplike, parameters as keyword by @agoose77 in #1921
• fix: backends should have defaults for user-facing operations by @agoose77 in #1940
• fix: consolidate regular indexing by @agoose77 in #1943
• fix: IndexedArray.project() preserves parameters. by @jpivarski in #1949
• fix: preserve strings in ak.ravel by @agoose77 in #1934
• fix: UnionArray.simplified preserves parameters. by @jpivarski in #1950

Other

• refactor: introduce backend as a higher abstraction than nplike by @agoose77 in #1922
• refactor: replace simplify_optiontype and simplify_uniontype with simplified classmethod by @jpivarski in #1928
• refactor: clarify input types for user overloads by @agoose77 in #1951
• refactor: removed the 'ak._util.extra' argument helper. by @jpivarski in #1955
• test: add @ioana's tests of to_arraylib. by @jpivarski in #1908
• test: cover the failure modes of unflatten by @agoose77 in #1930
• docs: fix broken build by @agoose77 in #1907
• docs: cleanup documentation by @agoose77 in #1946
• docs: fix shorthand by @agoose77 in #1952
• docs: retested and modernized all the docstrings in highlevel.py. by @jpivarski in #1954
• chore: fix NumPy bound & noxfile installs by @agoose77 in #1913
• chore: run yesqa by @agoose77 in #1915
• chore: update pre-commit hooks by @pre-commit-ci in #1920
• chore: update pre-commit hooks by @pre-commit-ci in #1953

Full Changelog: v2.0.0rc4...v2.0.0rc5