Added support for saving XML files!

Support for binary files will be coming later.

Utility/Formatting.cs

@@ -0,0 +1,108 @@
+using System.Globalization;
+using System.Linq;
+
+// This global class defines extension methods to numeric types
+// where I don't want system globalization to come into play.
+
+internal static class Formatting
+{
+    private static CultureInfo invariant => CultureInfo.InvariantCulture;
+
+    public static string ToInvariantString(this float value)
+    {
+        string result;
+
+        if (float.IsPositiveInfinity(value))
+            result = "INF";
+        else if (float.IsNegativeInfinity(value))
+            result = "-INF";
+        else if (float.IsNaN(value))
+            result = "NAN";
+        else
+            result = value.ToString(invariant);
+
+        return result;
+    }
+
+    public static string ToInvariantString(this double value)
+    {
+        string result;
+
+        if (double.IsPositiveInfinity(value))
+            result = "INF";
+        else if (double.IsNegativeInfinity(value))
+            result = "-INF";
+        else if (double.IsNaN(value))
+            result = "NAN";
+        else
+            result = value.ToString(invariant);
+
+        return result;
+    }
+
+    public static string ToInvariantString(this int value)
+    {
+        return value.ToString(invariant);
+    }
+
+    public static string ToInvariantString(this object value)
+    {
+        if (value is float)
+        {
+            float f = (float)value;
+            return f.ToInvariantString();
+        }
+        else if (value is double)
+        {
+            double d = (double)value;
+            return d.ToInvariantString();
+        }
+        else if (value is int)
+        {
+            int i = (int)value;
+            return i.ToInvariantString();
+        }
+        else
+        {
+            // Unhandled
+            return value.ToString();
+        }
+    }
+
+    public static float ParseFloat(string value)
+    {
+        float result;
+
+        if (value == "INF")
+            result = float.PositiveInfinity;
+        else if (value == "-INF")
+            result = float.NegativeInfinity;
+        else if (value == "NAN")
+            result = float.NaN;
+        else
+            result = float.Parse(value, invariant);
+
+        return result;
+    }
+
+    public static double ParseDouble(string value)
+    {
+        double result;
+
+        if (value == "INF")
+            result = double.PositiveInfinity;
+        else if (value == "-INF")
+            result = double.NegativeInfinity;
+        else if (value == "NAN")
+            result = double.NaN;
+        else
+            result = double.Parse(value, invariant);
+
+        return result;
+    }
+
+    public static int ParseInt(string s)
+    {
+        return int.Parse(s, invariant);
+    }
+}