Start using piecemeal includes in test files

tests/SelfTest/IntrospectiveTests/RandomNumberGeneration.tests.cpp

@@ -1,12 +1,9 @@
 /*
- *  Created by Martin on 06/10/2019.
- *
  *  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_test_macros.hpp>
 #include <catch2/catch_random_number_generator.h>
 
 TEST_CASE("Our PCG implementation provides expected results for known seeds", "[rng]") {