Merge pull request #149 from zcash/release/sapling-v0.4.0 #204

Job	Run time
Bitrot check	1m 54s
Latest build on ubuntu-latest	45s
Build target wasm32-wasi	1m 27s
Latest build on windows-latest	2m 47s
Clippy (MSRV)	1m 23s
Intra-doc links	1m 44s
Latest build on macOS-latest	40s
Rustfmt	11s
Test on ubuntu-latest	2m 52s
Test on windows-latest	3m 55s
Test on macOS-latest	2m 21s
	19m 59s

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