Merge ElementsProject/rust-elements#278: Clean up hashes and related … #718

Job	Run time
Bench - nightly toolchain	2m 21s
Docs - nightly toolchain	2m 9s
Test - nightly toolchain (recent)	6m 8s
Docs - stable toolchain	2m 3s
Cross test	2m 5s
Test - msrv toolchain (recent)	1m 41s
Test - stable toolchain (recent)	5m 45s
Test 32-bit version	1m 0s
Check WASM	37s
Lint - nightly toolchain	2m 32s
	26m 21s

Provide feedback