WIP: Import selection and editing code from Masonry #298

Job	Run time
cargo clippy (windows-latest)	28s
cargo check (msrv) (android) (armv7-linux-androideabi)	21s
cargo clippy (macos-latest)	20s
cargo check (msrv) (windows-latest)	25s
cargo clippy (android) (armv7-linux-androideabi)	35s
cargo check (msrv) (android) (aarch64-linux-android)	17s
cargo clippy (ubuntu-latest)	20s
cargo check (msrv) (macos-latest)	20s
cargo clippy (android) (aarch64-linux-android)	22s
cargo check (msrv) (android) (x86_64-linux-android)	22s
cargo check (msrv) (ubuntu-latest)	17s
cargo clippy (android) (x86_64-linux-android)	17s
cargo doc (windows-latest)	18s
cargo fmt	20s
cargo doc (macos-latest)	17s
cargo test (windows-latest)	21s
cargo doc (ubuntu-latest)	15s
typos	4s
cargo test (macos-latest)	17s
cargo test (ubuntu-latest)	15s
	6m 31s

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