Initial structure for adding support for comments.

src/parser/lesser_element.rs

@@ -5,3 +5,8 @@ pub struct Paragraph<'s> {
     pub source: &'s str,
     pub children: Vec<Object<'s>>,
 }
+
+#[derive(Debug)]
+pub struct Comment<'s> {
+    pub source: &'s str,
+}