Start using piecemeal includes in test files

tests/SelfTest/IntrospectiveTests/CmdLine.tests.cpp

@@ -1,12 +1,11 @@
 /*
- *  Created by Phil on 13/5/2013.
- *  Copyright 2014 Two Blue Cubes Ltd. All rights reserved.
- *
  *  Distributed under the Boost Software License, Version 1.0. (See accompanying
  *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  */
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_approx.h>
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_matchers_string.h>
 #include <catch2/catch_test_spec_parser.h>
 #include <catch2/catch_test_case_info.h>
 #include <catch2/catch_config.hpp>