Example usage:

 object Options extends CommandLineParser {
     val exclude = new StringOption('x', "exclude", "Exclude the given file") with AllowAll
     val version = new Flag("version", "Show version info") with AllowNone
     override def helpHeader = """
         |  SomeTool v0.1
         |  (c) 1908 SomeCorp
         |
         |""".stripMargin
 }

 Options.parseOrHelp(argv) { cmd =>
     if(cmd(Options.version)) {
         ...
     }
 }