Fix attention starting and ending in different links

Example:

```markdown
[*]() [*]()
```

There was already code for:

```markdown
[*]() x*.

*x [*]().
```

But that wasn’t correct for attention at the same depth but in different places.

Closes GH-21.

Co-authored-by: Christian Murphy <christian.murphy.42@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/fuzz.rs b/tests/fuzz.rs
index 522e32f..e6816e6 100644
--- a/tests/fuzz.rs
+++ b/tests/fuzz.rs
@@ -104,5 +104,11 @@ fn fuzz() -> Result<(), String> {
         "9: autolink literals that end in table cell delimiter (GH-20)"
     );
 
+    assert_eq!(
+        to_html_with_options("[*]() [*]()", &Options::gfm()),
+        Ok("<p><a href=\"\">*</a> <a href=\"\">*</a></p>".into()),
+        "10: attention in different links (GH-21)"
+    );
+
     Ok(())
 }