support streams containing only carriage returns. handle comments in arrays and dictionaries

* while the pdf specification says stream data should follow a newline following a stream operator some files have only a carriage return following the stream operator.
* since comment tokens may appear inside an array or dictionary we ignore them if they occur here since they will break interpretation of the dictionary or array contents.

src/UglyToad.PdfPig/Tokenization/ArrayTokenizer.cs

@@ -26,6 +26,11 @@
             while (!CurrentByteEndsCurrentArray(inputBytes, previousToken) && scanner.MoveNext())
             {
                 previousToken = scanner.CurrentToken;
+
+                if (scanner.CurrentToken is CommentToken)
+                {
+                    continue;
+                }
                 
                 contents.Add(scanner.CurrentToken);
             }

src/UglyToad.PdfPig/Tokenization/DictionaryTokenizer.cs

@@ -48,6 +48,11 @@
 
             while (coreScanner.MoveNext())
             {
+                if (coreScanner.CurrentToken is CommentToken)
+                {
+                    continue;
+                }
+
                 tokens.Add(coreScanner.CurrentToken);
             }
 

src/UglyToad.PdfPig/Tokenization/Scanner/PdfTokenScanner.cs

@@ -229,14 +229,22 @@
                 return false;
             }
 
+            // While the specification demands a \n we have seen files with \r only in the wild.
+            var hadWhiteSpace = false;
             if (inputBytes.CurrentByte == '\r')
             {
+                hadWhiteSpace = true;
                 inputBytes.MoveNext();
             }
 
             if (inputBytes.CurrentByte != '\n')
             {
-                return false;
+                if (!hadWhiteSpace)
+                {
+                    return false;
+                }
+
+                inputBytes.Seek(inputBytes.CurrentOffset - 1);
             }
 
             // Store where we started reading the first byte of data.