Merge #94: simplicity: swap program and witness data in satisfaction

7464550 simplicity: swap program and witness data in satisfaction (Andrew Poelstra)

Pull request description:

  These are backward, which I noticed when constructing a Simplicity transaction for Liquid Testnet. There isn't an easy way to unit test this but I confirmed that the new order is the correct one on the live network.

ACKs for top commit:
  RCasatta:
    utACK 7464550

Tree-SHA512: 9257f517c32f93ff2fd715ff4ee5343b8dff5fcbb621d9586cd96cc45086860f29ffc2c401a341473927b226edb2525b3253e4b1a215e9d2b86a84b08f206876

src/descriptor/tr.rs

@@ -554,7 +554,7 @@ impl<'a, Pk: ToPublicKey, Ext: ParseableExt> TapLeafScript<'a, Pk, Ext> {
                 let satisfier = crate::simplicity::SatisfierWrapper::new(satisfier);
                 let program = sim.satisfy(&satisfier).map_err(|_| Error::CouldNotSatisfy)?;
                 let (program_bytes, witness_bytes) = program.encode_to_vec();
-                Ok(vec![program_bytes, witness_bytes])
+                Ok(vec![witness_bytes, program_bytes])
             }
         }
     }