`BoxedUint` support #137

Job	Run time
tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	59s
slow-tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	3m 3s
tests (x86_64-unknown-linux-gnu, stable)	41s
build-wasm (1.73.0, wasm32-unknown-unknown)	17s
build-benchmarks	2m 36s
slow-tests (x86_64-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	2m 56s
build-wasm (stable, wasm32-unknown-unknown)	15s
clippy	2m 22s
codecov	45s
rustfmt	14s
	14m 8s

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