Add lib.rs, scaffold testing

src/formats.rs

@@ -124,3 +124,12 @@ pub fn deserialize_graph(in_format: &Format, serial: &str) -> Graph {
         },
     }
 }
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn smoke() {
+        let n = true;
+        assert!(n);
+    }
+}