title: Reporting unknown arguments using CommandLineParser
body: <p>Is there any way to make the <a href="http://commandline.codeplex.com/" rel="noreferrer">Command Line Parser library</a> report unknown arguments?</p>
  
  <p>Given the following options class:</p>
  
  <pre><code>public class Options
  {
      [Option('i', "int-option", DefaultValue = 10, HelpText = "Set the int")]
      public int IntOption { get; set; }
  
      [ParserState]
      public IParserState LastParserState { get; set; }
  
      [HelpOption]
      public string GetUsage()
      {
          return HelpText.AutoBuild(this, 
              HelpText.DefaultParsingErrorsHandler(this, current));
      }
  }
  </code></pre>
  
  <p>And the following program:</p>
  
  <pre><code>var options = new Options();
  var parser = new Parser(settings =&gt;
  {
      settings.HelpWriter = Console.Error;
      settings.IgnoreUnknownArguments = false;
  });
  
  if (parser.ParseArgumentsStrict(args, options))
  {
      Console.WriteLine("Int value set: {0}", options.IntOption);
  }
  </code></pre>
  
  <p>When calling the program with "MyProgram.exe --unknown"
  I just get the default usage information, but no mention of what error made the parsing fail. I'd like to get some kind of indication to the user what went wrong.</p>