Implement the new fields for footnote definitions.

src/parser/footnote_definition.rs

@@ -75,6 +75,7 @@ where
     let parser_context = parser_context.with_additional_node(&contexts[2]);
     let element_matcher = parser_with_context!(element(true))(&parser_context);
     let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
+    let before_contents = remaining;
     let (mut remaining, (mut children, _exit_contents)) =
         many_till(include_input(element_matcher), exit_matcher)(remaining)?;
 
@@ -90,13 +91,16 @@ where
         }
     }
 
-    let (remaining, _trailing_ws) =
+    let contents = get_consumed(before_contents, remaining);
+    let (remaining, post_blank) =
         maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;
     let source = get_consumed(input, remaining);
     Ok((
         remaining,
         FootnoteDefinition {
             source: source.into(),
+            contents: Some(contents.into()),
+            post_blank: post_blank.map(Into::<&str>::into),
             affiliated_keywords: parse_affiliated_keywords(
                 context.get_global_settings(),
                 affiliated_keywords,