Wrap inline footnote definitions in a paragraph tag.

This is to match the behavior of the upstream org html exporter.

src/intermediate/paragraph.rs

@@ -29,3 +29,16 @@ intermediate!(
         })
     }
 );
+
+impl IParagraph {
+    pub(crate) async fn artificial<'orig, 'parse>(
+        _intermediate_context: crate::intermediate::IntermediateContext<'orig, 'parse>,
+        children: Vec<IObject>,
+        post_blank: organic::types::PostBlank,
+    ) -> Result<IParagraph, CustomError> {
+        Ok(IParagraph {
+            children,
+            post_blank,
+        })
+    }
+}

src/intermediate/registry.rs

@@ -5,6 +5,8 @@ use std::collections::HashMap;
 
 use super::ast_node::IAstNode;
 use super::ast_node::IntoIAstNode;
+use super::IObject;
+use super::IParagraph;
 use super::IntermediateContext;
 
 type IdCounter = u16;
@@ -148,13 +150,20 @@ async fn convert_reference_contents<'orig, 'parse>(
     intermediate_context: IntermediateContext<'orig, 'parse>,
     contents: &'orig Vec<Object<'parse>>,
 ) -> Result<Vec<IAstNode>, CustomError> {
-    let contents = {
+    let children = {
         let mut ret = Vec::new();
         for obj in contents.iter() {
-            ret.push(obj.into_ast_node(intermediate_context.clone()).await?);
+            ret.push(IObject::new(intermediate_context.clone(), obj).await?);
         }
         ret
     };
+    let containing_paragraph =
+        IParagraph::artificial(intermediate_context.clone(), children, 0).await?;
+    let contents = {
+        let mut ret = Vec::new();
+        ret.push(IAstNode::Paragraph(containing_paragraph));
+        ret
+    };
 
     Ok(contents)
 }