Fixed an issue on some compilers with implicit conversion from nullptr to Ptr

- also cleaned up some warnings to do with CATCH_NULL

projects/SelfTest/ConditionTests.cpp

@@ -6,7 +6,8 @@
  *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  */
 #ifdef __clang__
-#pragma clang diagnostic ignored "-Wpadded"
+#   pragma clang diagnostic ignored "-Wpadded"
+#   pragma clang diagnostic ignored "-Wc++98-compat"
 #endif
 
 #include "catch.hpp"