Changed all .hpp extensions to .h where there is now a corresponding .cpp

include/internal/catch_run_context.cpp

@@ -1,4 +1,4 @@
-#include "catch_run_context.hpp"
+#include "catch_run_context.h"
 #include "catch_context.h"
 #include "catch_enforce.h"
 #include "catch_random_number_generator.h"