Currently we pass a Vec. This requires an extra allocation and copy of all elements if a caller doesn't have a Vec already, which is at least 95% of cases.
Another, a smaller issue, we have a function util::to_hex and some structs implement to_hex() on top of it, so we have a mix of it in the code. This PR introduces a trait and a blanket impl for AsRef<[u8]> which brings a uniform API (obj.to_hex()). One unfortunate case is arrays of size bigger than 32 - Rust doesn't implement AsRef for them so it requires an ugly hack (&array[..]).to_hex().
* Implement simple zeroing of BlindingFactor in Drop
* rustfmt
* Make Debug implementation for BlindingFactor empty
* Implement BlindingFactor zeroing unit test
* mnemonic.rs: fix deprecated warning in test_bip39_random test
* Use zeroize crate to clear BlindingFactor
* Fix comment and implement dummy Debug trait for BlindingFactor
* Fix formatter
