Try to add support for link-references and chicken out

This is going to be far far more difficult than I thought and will
require a much larger refactor.

test/links_loader_test.dart

@@ -46,6 +46,13 @@ void main() {
       expect(links[3].alt, "alt-text");
       expect(links[3].wikiTerm.isEmpty, true);
 
+      /*
+      expect(links[4].filePath, "/tmp/foam.md");
+      expect(links[4].publicTerm, "Foam");
+      expect(links[4].alt, "foam");
+      expect(links[4].wikiTerm.isEmpty, true);
+      */
+
       expect(links.length, 4);
     });
 
@@ -96,4 +103,6 @@ Foam is licensed under the [MIT license](license).
       expect(links[4].alt, "Autogenerated link references");
     });
   });
+
+  // Add a test for linking to a header in another Note
 }