Merge #517: Use hash_newtype macro instead of the hash256 module

0b482cd Use hash_newtype macro instead of the hash256 module (Tobin C. Harding)
4eaf261 Fix CI (sanket1729)

Pull request description:

  We currently implement the `hash256::Hash` type manually however there is a macro in `bitcoin::hashes` that can do that for us.

  For context, the `hash256::Hash` type exists solely to enable the type to display forwards since `hashes::sha256d` displays backwards. The `hash_newtype` macro takes an argument to configure display.

ACKs for top commit:
  apoelstra:
    ACK 0b482cd
  sanket1729:
    ACK 0b482cd

Tree-SHA512: 4f5cb44c3fc65b986375565b1c613e99784bfbc5da30542283e39552f986d07ab1876636857d207d9c5d9497719dfcd28ecc1125671f78f171fb041aa770f148

Author: sanket1729

README.md

@@ -44,6 +44,8 @@ you may need to pin as follows:
 ```
 cargo update --package url --precise 2.2.2
 cargo update --package form_urlencoded --precise 1.0.1
+cargo update -p once_cell --precise 1.13.1
+cargo update -p bzip2 --precise 0.4.2
 ```
 
 ## Contributing

contrib/test.sh

@@ -15,6 +15,7 @@ if cargo --version | grep "1\.41\.0"; then
     cargo update -p url --precise 2.2.2
     cargo update -p form_urlencoded --precise 1.0.1
     cargo update -p once_cell --precise 1.13.1
+    cargo update -p bzip2 --precise 0.4.2
 fi
 
 # Pin dependencies required to build with Rust 1.47.0

src/miniscript/hash256.rs

@@ -27,7 +27,6 @@ pub mod analyzable;
 pub mod astelem;
 pub(crate) mod context;
 pub mod decode;
-pub mod hash256;
 pub mod iter;
 pub mod lex;
 pub mod limits;
@@ -459,6 +458,14 @@ impl_from_str!(
 
 serde_string_impl_pk!(Miniscript, "a miniscript", Ctx; ScriptContext);
 
+/// Provides a Double SHA256 `Hash` type that displays forwards.
+pub mod hash256 {
+    use bitcoin::hashes::{hash_newtype, sha256d};
+
+    #[rustfmt::skip]
+    hash_newtype!(Hash, sha256d::Hash, 32, doc = "A bitcoin block hash.", false);
+}
+
 #[cfg(test)]
 mod tests {