Fix ASCII entity resolution (fixes #9)

Entity: line 1: parser error : Couldn't find end of Start Tag ref
=epub%20leseprobe&utm_campaign=m%C3%A4dchen%20mit%20den%20engelsh%C3%A4nden"
^

Change-Id: Ic57b654bbfe37bb5ea2d4307e8e8deb83fb1cf22
diff --git a/t/tei.t b/t/tei.t
index 98b945e..f5fa39e 100644
--- a/t/tei.t
+++ b/t/tei.t
@@ -140,7 +140,11 @@
   is(replace_entities('A'), 'A');
   is(replace_entities('«'), replace_entities('«'));
   is(replace_entities('A'), 'A');
-  is(replace_entities('&<>'), '&<>')
+  is(replace_entities('&<>'), '&<>');
+  is(replace_entities('"'), '"');
+  is(replace_entities('&'), '&');
+  is(replace_entities('''), ''');
+  is(replace_entities('<'), '<');
 };
 
 done_testing;