more documentation and remove unused code

src/UglyToad.Pdf/Exceptions/PdfDocumentFormatException.cs

@@ -3,6 +3,11 @@
     using System;
     using System.Runtime.Serialization;
 
+    /// <inheritdoc />
+    /// <summary>
+    /// This exception will be thrown where the contents of the PDF document do not match the specification in such a way that it
+    /// renders the document unreadable.
+    /// </summary>
     [Serializable]
     public class PdfDocumentFormatException : Exception
     {
@@ -13,6 +18,10 @@
         //    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncscol/html/csharp07192001.asp
         //
 
+        /// <inheritdoc />
+        /// <summary>
+        /// Create a new <see cref="T:UglyToad.Pdf.Exceptions.PdfDocumentFormatException" />.
+        /// </summary>
         public PdfDocumentFormatException()
         {
         }

src/UglyToad.Pdf/Util/Hex.cs

@@ -48,20 +48,6 @@
             output.Write(HexBytes[GetLowNibble(b)]);
         }
 
-        /** 
-         * Writes the given byte array as hex value to the given output stream.
-         * @param bytes the byte array to be written
-         * @param output the output stream to be written to
-         * @throws IOException exception if anything went wrong
-         */
-        public static void WriteHexBytes(byte[] bytes, BinaryWriter output)
-        {
-            foreach (var b in bytes)
-            {
-                WriteHexByte(b, output);
-            }
-        }
-
         /**
          * GetLongOrDefault the high nibble of the given byte.
          * 

src/UglyToad.Pdf/Util/ParsePosition.cs

@@ -1,20 +0,0 @@
-namespace UglyToad.Pdf.Util
-{
-    internal class ParsePosition
-    {
-        public int Index { get; set; }
-
-        public int ErrorIndex { get; set; }
-
-        public ParsePosition(int index)
-        {
-            Index = index;
-            ErrorIndex = -1;
-        }
-
-        public override string ToString()
-        {
-            return $"{Index} (Error: {ErrorIndex})";
-        }
-    }
-}