add test for comment in dictionary from #145

check that we correctly handle the case where a comment appears inside a dictionary, this was handled by commit 3084a9. use list internally to dictionary tokenizer to avoid interface performance penalties.

src/UglyToad.PdfPig.Tokenization/DictionaryTokenizer.cs

@@ -60,7 +60,7 @@
             return true;
         }
 
-        private static Dictionary<NameToken, IToken> ConvertToDictionary(IReadOnlyList<IToken> tokens)
+        private static Dictionary<NameToken, IToken> ConvertToDictionary(List<IToken> tokens)
         {
             var result = new Dictionary<NameToken, IToken>();