Add support for target links.

src/intermediate/registry.rs

@@ -14,7 +14,7 @@ type IdCounter = u16;
 #[derive(Debug)]
 pub(crate) struct Registry<'orig, 'parse> {
     id_counter: IdCounter,
-    targets: HashMap<&'parse str, String>,
+    targets: HashMap<String, String>,
     footnote_ids: Vec<(Option<&'parse str>, Vec<IAstNode>)>,
     footnote_reference_counts: HashMap<&'parse str, usize>,
     on_deck_footnote_ids: HashMap<&'parse str, &'orig Vec<Element<'parse>>>,
@@ -31,8 +31,8 @@ impl<'orig, 'parse> Registry<'orig, 'parse> {
         }
     }
 
-    pub(crate) fn get_target<'reg>(&'reg mut self, body: &'parse str) -> &'reg String {
-        self.targets.entry(body).or_insert_with(|| {
+    pub(crate) fn get_target<S: Into<String>>(&mut self, body: S) -> &String {
+        self.targets.entry(body.into()).or_insert_with(|| {
             self.id_counter += 1;
             format!("target_{}", self.id_counter)
         })