Readme and clippy cleanups

src/error.rs

@@ -56,9 +56,10 @@ impl fmt::Display for Traceback {
     }
 }
 
-impl std::convert::Into<String> for Traceback {
-    fn into(self) -> String {
-        format!("{}", self)
+
+impl std::convert::From<Traceback> for String {
+    fn from(arg: Traceback) -> Self {
+        format!("{}", arg)
     }
 }