Handle greater blocks with only blank space inside them.

src/parser/lesser_element.rs

@@ -1,4 +1,4 @@
-use super::object::Object;
+use super::object::{Object, TextMarkup};
 
 #[derive(Debug)]
 pub struct Paragraph<'s> {
@@ -10,3 +10,14 @@ pub struct Paragraph<'s> {
 pub struct Comment<'s> {
     pub source: &'s str,
 }
+
+impl<'s> Paragraph<'s> {
+    pub fn of_text(input: &'s str) -> Self {
+        let mut objects = Vec::with_capacity(1);
+        objects.push(Object::TextMarkup(TextMarkup { source: input }));
+        Paragraph {
+            source: input,
+            children: objects,
+        }
+    }
+}