ZArchive support (#75)

* ZArchive support

* Fix offset record format

* Simplfiy Extensions

* Delete unused writers and test data

* Rework reader

* Fix build

SabreTools.Data.Extensions/ZArchiveExtensions.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Text;
+using SabreTools.Data.Models.ZArchive;
+using SabreTools.Numerics;
+
+namespace SabreTools.Data.Extensions
+{
+    public static class ZArchiveExtensions
+    {
+        /// <summary>
+        /// Retrieves the name of the specified node from the NameTable
+        /// </summary>
+        /// <param name="node">Node in the file tree</param>
+        /// <param name="nameTable">ZArchive NameTable</param>
+        /// <returns>UTF-8 string representing node's name</returns>
+        public static string? GetName(this FileDirectoryEntry node, NameTable nameTable)
+        {
+            // Check for a valid offset into the NameTable
+            uint nameOffset = node.NameOffsetAndTypeFlag & Constants.RootNode;
+            if (nameOffset == Constants.RootNode)
+                return null;
+
+            // Get the index into the name table
+            var index = Array.IndexOf(nameTable.NameTableOffsets, nameOffset);
+            if (index < 0)
+                return null;
+
+            // Get the name entry for the requested index
+            var nameEntry = nameTable.NameEntries[index];
+            if (nameEntry is null)
+                return null;
+
+            // Decode name to UTF-8
+            return Encoding.UTF8.GetString(nameEntry.NodeName);
+        }
+    }
+}