Add `atan2` and improve accuracy of `atan` #351

Job	Run time
build (ubuntu-latest, Release, clang, 3.10)	4m 46s
build (ubuntu-latest, Release, clang, 3.11)	4m 58s
build (ubuntu-latest, Release, clang, 3.12)	4m 44s
build (windows-2019, Release, cl, 3.10)	5m 27s
build (windows-2019, Release, cl, 3.11)	5m 0s
build (windows-2019, Release, cl, 3.12)	6m 4s
build (macos-12, Release, clang, 3.10)	2m 45s
build (macos-12, Release, clang, 3.11)	3m 1s
build (macos-12, Release, clang, 3.12)	3m 0s
build (macos-13, Release, clang, 3.10)	3m 14s
build (macos-13, Release, clang, 3.11)	3m 11s
build (macos-13, Release, clang, 3.12)	7m 25s
build (macos-14, Release, clang, 3.10)	1m 45s
build (macos-14, Release, clang, 3.11)	1m 54s
build (macos-14, Release, clang, 3.12)	1m 45s
	58m 59s

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