Wt::WRun throws on unknown command line parameters

Wt::WRun throws if unknown command line parameters are present. Since Wt::WRun() is mostly a helper function, silent-ignore behavior seems reasonable. According to http://www.boost.org/doc/libs/1_56_0/doc/html/program_options/howto.html#idp344642720 "To allow unregistered options on the command line, you need to use the basic_command_line_parser class for parsing (not parse_command_line) and call the allow_unregistered method of that class".