WIP: Import selection and editing code from Masonry #310

Job	Run time
cargo check (msrv) (android) (armv7-linux-androideabi)	57s
cargo clippy (windows-latest)	44s
cargo check (msrv) (android) (aarch64-linux-android)	55s
cargo check (msrv) (windows-latest)	55s
cargo clippy (macos-latest)	39s
cargo clippy (android) (armv7-linux-androideabi)	52s
cargo check (msrv) (android) (x86_64-linux-android)	52s
cargo check (msrv) (macos-latest)	55s
cargo clippy (ubuntu-latest)	50s
cargo clippy (android) (aarch64-linux-android)	48s
cargo check (msrv) (ubuntu-latest)	52s
cargo clippy (android) (x86_64-linux-android)	52s
cargo doc (windows-latest)	3m 18s
cargo fmt	10s
cargo doc (macos-latest)	1m 8s
cargo doc (ubuntu-latest)	1m 6s
cargo test (windows-latest)	4m 41s
typos	5s
cargo test (macos-latest)	1m 49s
cargo test (ubuntu-latest)	1m 57s
	24m 25s

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