Allow simpler syntax in namespace mapping files

XmlSchemaClassGenerator.Console/Program.cs

@@ -68,6 +68,7 @@ static void Main(string[] args)
  { "h|help", "show this message and exit", v => showHelp = v != null },
  { "n|namespace=", @"map an XML namespace to a C# namespace
 Separate XML namespace and C# namespace by '='.
+A single value (no '=') is taken as the C# namespace the empty XML namespace is mapped to.
 One option must be given for each namespace to be mapped.
 A file name may be given by appending a pipe sign (|) followed by a file name (like schema.xsd) to the XML namespace.
 If no mapping is found for an XML namespace, a name is generated automatically (may fail).", v => namespaces.Add(v) },
@@ -269,6 +270,9 @@ private static void ParseNamespaceFiles(List<string> namespaces, List<string> na
  {
  var parts = line.Split('=');
 
+ if (parts.Length == 1)
+ parts = new[] { string.Empty, parts[0] };
+
  if (parts.Length != 2)
  {
  System.Console.WriteLine($"{namespaceFile}:{number}: Line format is XML namespace = C# namespace [file name]");