Derive `Clone` for `PlainEditor` #372

Job	Run time
cargo check (msrv) (android) (armv7-linux-androideabi)	1m 4s
cargo clippy (windows-latest)	5m 7s
cargo check (msrv) (android) (aarch64-linux-android)	1m 1s
cargo check (msrv) (windows-latest)	4m 49s
cargo clippy (macos-latest)	2m 3s
cargo clippy (android) (armv7-linux-androideabi)	2m 5s
cargo check (msrv) (android) (x86_64-linux-android)	1m 3s
cargo check (msrv) (macos-latest)	1m 19s
cargo clippy (android) (aarch64-linux-android)	2m 8s
cargo clippy (ubuntu-latest)	2m 32s
cargo check (msrv) (ubuntu-latest)	1m 14s
cargo clippy (android) (x86_64-linux-android)	1m 56s
cargo doc (windows-latest)	2m 44s
cargo fmt	23s
cargo test (windows-latest)	4m 58s
cargo doc (macos-latest)	1m 4s
cargo test (macos-latest)	1m 39s
cargo doc (ubuntu-latest)	1m 10s
cargo test (ubuntu-latest)	2m 2s
typos	4s
	40m 25s

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