STYLE: IOstreams with float/double instead of floatScalar/doubleScalar

- consistent with defining IO of int32_t/int64_t and with recent
  changes to ensightFile. Using the primitives directly instead of
  typedefs to them makes the code somewhat less opaque.

applications/test/TestTools/TestTools.H

@@ -28,15 +28,14 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-using namespace Foam;
-
-#include "floatScalar.H"
-#include "doubleScalar.H"
+#include "scalar.H"
 #include "complex.H"
 #include "Matrix.H"
 #include "Random.H"
 #include <chrono>
 
+using namespace Foam;
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 // Total number of unit tests