Add a compare_properties variant with support for additional properties.

src/compare/diff.rs

@@ -542,11 +542,10 @@ fn new_compare_heading<'b, 's>(
     let mut child_status = Vec::new();
     let mut message = None;
 
-    let additional_property_names = rust
+    let additional_property_names: Vec<String> = rust
         .get_additional_properties()
-        .map(|node_property| EmacsField::Required(node_property.property_name));
-
-    // TODO: This needs to support additional properties from the property drawer
+        .map(|node_property| format!(":{}", node_property.property_name))
+        .collect();
 
     compare_children(
         source,
@@ -561,6 +560,10 @@ fn new_compare_heading<'b, 's>(
         source,
         emacs,
         rust,
+        additional_property_names
+            .iter()
+            .map(String::as_str)
+            .map(EmacsField::Required),
         (
             EmacsField::Required(":level"),
             |r| Some(r.level),