Seal Encoding classes

src/UglyToad.PdfPig.Fonts/Encodings/DifferenceBasedEncoding.cs

@@ -8,7 +8,7 @@
     /// <summary>
     /// Created by combining a base encoding with the differences.
     /// </summary>
-    public class DifferenceBasedEncoding : Encoding
+    public sealed class DifferenceBasedEncoding : Encoding
     {
         /// <inheritdoc />
         public override string EncodingName { get; } = "Difference Encoding";

src/UglyToad.PdfPig.Fonts/Encodings/MacExpertEncoding.cs

@@ -1,8 +1,6 @@
 namespace UglyToad.PdfPig.Fonts.Encodings
 {
-    using Core;
-
-    internal class MacExpertEncoding : Encoding
+    internal sealed class MacExpertEncoding : Encoding
     {
         /// <summary>
         /// Table of octal character codes and their corresponding names.

src/UglyToad.PdfPig.Fonts/Encodings/MacOsRomanEncoding.cs

@@ -1,12 +1,10 @@
 namespace UglyToad.PdfPig.Fonts.Encodings
 {
-    using Core;
-
     /// <inheritdoc />
     /// <summary>
     /// Similar to the <see cref="T:UglyToad.PdfPig.Fonts.Encodings.MacRomanEncoding" /> with 15 additional entries.
     /// </summary>
-    public class MacOsRomanEncoding : MacRomanEncoding
+    public sealed class MacOsRomanEncoding : MacRomanEncoding
     {
         private static readonly (int, string)[] EncodingTable =
         {

src/UglyToad.PdfPig.Fonts/Encodings/MacRomanEncoding.cs

@@ -1,8 +1,5 @@
 namespace UglyToad.PdfPig.Fonts.Encodings
-{
-    using Core;
-    using System.Diagnostics;
-
+{
     /// <summary>
     /// The Mac Roman encoding.
     /// </summary>

src/UglyToad.PdfPig.Fonts/Encodings/StandardEncoding.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// The standard PDF encoding.
     /// </summary>
-    public class StandardEncoding : Encoding
+    public sealed class StandardEncoding : Encoding
     {
         private static readonly (int, string)[] EncodingTable =
         {

src/UglyToad.PdfPig.Fonts/Encodings/SymbolEncoding.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// Symbol encoding.
     /// </summary>
-    public class SymbolEncoding : Encoding
+    public sealed class SymbolEncoding : Encoding
     {
         /// <summary>
         /// EncodingTable for Symbol

src/UglyToad.PdfPig.Fonts/Encodings/WinAnsiEncoding.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// Windows ANSI encoding.
     /// </summary>
-    public class WinAnsiEncoding : Encoding
+    public sealed class WinAnsiEncoding : Encoding
     {
         /// <summary>
         /// The encoding table is taken from the Appendix of the specification.

src/UglyToad.PdfPig.Fonts/Encodings/ZapfDingbatsEncoding.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// Zapf Dingbats encoding.
     /// </summary>
-    public class ZapfDingbatsEncoding : Encoding
+    public sealed class ZapfDingbatsEncoding : Encoding
     {
         /// <summary>
         /// EncodingTable for ZapfDingbats