Numerically approximate arc perimeter #680

Job	Run time
cargo test (windows-latest)	1m 0s
cargo clippy (windows-latest)	1m 28s
cargo test (macos-latest)	24s
cargo clippy (macos-latest)	1m 2s
cargo check (msrv) (wasm32)	21s
cargo test (ubuntu-latest)	24s
cargo check (msrv) (windows-latest)	1m 9s
cargo clippy (ubuntu-latest)	42s
cargo check (msrv) (macos-latest)	29s
cargo check (msrv) (ubuntu-latest)	2m 6s
cargo clippy (wasm32)	42s
cargo doc	26s
cargo fmt	22s
cargo test (wasm32)	16s
typos	7s
	10m 58s

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