Derive `Default` on enums. #249

Job	Run time
cargo fmt	20s
cargo clippy (windows-latest)	2m 24s
cargo clippy (android) (armv7-linux-androideabi)	1m 2s
cargo check (msrv) (android) (armv7-linux-androideabi)	46s
cargo doc (windows-latest)	1m 31s
cargo clippy (android) (aarch64-linux-android)	1m 3s
cargo check (msrv) (android) (aarch64-linux-android)	46s
cargo clippy (macos-latest)	1m 10s
cargo doc (macos-latest)	36s
cargo clippy (ubuntu-latest)	1m 13s
cargo check (msrv) (android) (x86_64-linux-android)	43s
cargo clippy (android) (x86_64-linux-android)	1m 4s
cargo doc (ubuntu-latest)	25s
cargo test (windows-latest)	2m 6s
typos	4s
cargo check (msrv) (windows-latest)	1m 54s
cargo test (macos-latest)	39s
cargo check (msrv) (macos-latest)	56s
cargo test (ubuntu-latest)	40s
cargo check (msrv) (ubuntu-latest)	50s
	20m 12s

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