Do not parse the lesser block contents during parsing, but rather only if the contents are requested.

This seemed like an unnecessary allocation during parsing, especially considering we throw away some parses based on whether or not we found radio targets in the source.

src/compare/diff.rs

@@ -1576,7 +1576,7 @@ fn compare_example_block<'b, 's>(
         [],
         (
             EmacsField::Required(":value"),
-            |r| Some(&r.contents),
+            |r| Some(r.get_contents()),
             compare_property_quoted_string
         ),
         (
@@ -1654,7 +1654,7 @@ fn compare_export_block<'b, 's>(
         ),
         (
             EmacsField::Required(":value"),
-            |r| Some(&r.contents),
+            |r| Some(r.get_contents()),
             compare_property_quoted_string
         )
     ) {
@@ -1702,7 +1702,7 @@ fn compare_src_block<'b, 's>(
         ),
         (
             EmacsField::Required(":value"),
-            |r| Some(&r.contents),
+            |r| Some(r.get_contents()),
             compare_property_quoted_string
         ),
         (