Initial code structure for regular links.

src/parser/object.rs

@@ -111,3 +111,9 @@ impl<'s> Source<'s> for Verbatim<'s> {
         self.source
     }
 }
+
+impl<'s> Source<'s> for RegularLink<'s> {
+    fn get_source(&'s self) -> &'s str {
+        self.source
+    }
+}