Add underivable impls to Signature.

src/signature.rs

@@ -1,3 +1,5 @@
+use std::{convert, fmt};
+
 /// A RedJubJub signature.
 pub struct Signature(pub [u8; 64]);
 
@@ -12,3 +14,29 @@ impl From<Signature> for [u8; 64] {
         s.0
     }
 }
+
+// These impls all only exist because of array length restrictions.
+
+impl fmt::Debug for Signature {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_tuple("Signature").field(&self.0[..]).finish()
+    }
+}
+
+impl Copy for Signature {}
+
+impl Clone for Signature {
+    fn clone(&self) -> Self {
+        let mut bytes = [0; 64];
+        bytes[..].copy_from_slice(&self.0[..]);
+        Self(bytes)
+    }
+}
+
+impl PartialEq for Signature {
+    fn eq(&self, other: &Self) -> bool {
+        self.0[..] == other.0[..]
+    }
+}
+
+impl Eq for Signature {}