GUI: Add load options dialog with ELF image base option

Il2CppInspector.GUI/HexStringValueConverter.cs

@@ -0,0 +1,34 @@
+// Copyright (c) 2020 Katy Coe - https://www.djkaty.com - https://github.com/djkaty
+// All rights reserved
+
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Text;
+using System.Windows;
+using System.Windows.Data;
+
+namespace Il2CppInspector.GUI
+{
+    internal class HexStringValueConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+            if (value == null || targetType != typeof(string))
+                return DependencyProperty.UnsetValue;
+
+            return ((ulong) value).ToString("x16");
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
+            if (value == null || targetType != typeof(ulong?))
+                return DependencyProperty.UnsetValue;
+
+            try {
+                return System.Convert.ToUInt64((string) value, 16);
+            }
+            catch {
+                return DependencyProperty.UnsetValue;
+            }
+        }
+    }
+}