`BoxedUint` support #142

Job	Run time
codecov	48s
build-benchmarks	2m 44s
build-wasm (1.73.0, wasm32-unknown-unknown)	19s
clippy	2m 21s
build-wasm (stable, wasm32-unknown-unknown)	15s
rustfmt	19s
slow-tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	3m 2s
tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	58s
slow-tests (x86_64-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	3m 31s
tests (x86_64-unknown-linux-gnu, stable)	2m 18s
	16m 35s

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