Write a test runner for Monero transactions

Also includes a few fixes for the library itself. Supersedes #172.

coins/monero/src/wallet/mod.rs

@@ -18,7 +18,7 @@ pub mod address;
 use address::{Network, AddressType, AddressMeta, MoneroAddress};
 
 mod scan;
-pub use scan::SpendableOutput;
+pub use scan::{ReceivedOutput, SpendableOutput};
 
 pub(crate) mod decoys;
 pub(crate) use decoys::Decoys;

coins/monero/src/wallet/send/mod.rs

@@ -362,7 +362,7 @@ impl SignableTransaction {
 
   /// Sign this transaction.
   pub async fn sign<R: RngCore + CryptoRng>(
-    &mut self,
+    mut self,
     rng: &mut R,
     rpc: &Rpc,
     spend: &Zeroizing<Scalar>,