ENH: relocate zero_one to pTraits, allows reuse for scalar clamping

ENH: add pTraits and IO for std::int8_t

STYLE: cull some implicitly available includes

- pTraits.H is included by label/scalar etc
- zero.H is included by UList

STYLE: cull redundant forward declarations for Istream/Ostream

applications/utilities/mesh/advanced/selectCells/edgeStats.H

@@ -34,8 +34,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef edgeStats_H
-#define edgeStats_H
+#ifndef Foam_edgeStats_H
+#define Foam_edgeStats_H
 
 #include "direction.H"
 #include "scalar.H"
@@ -45,9 +45,8 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
+// Forward Declarations
 class polyMesh;
-class Ostream;
 class twoDPointCorrector;
 
 /*---------------------------------------------------------------------------*\

applications/utilities/preProcessing/PDR/pdrFields/obstacles/PDRobstacleTypes.C

@@ -62,7 +62,7 @@ namespace Foam
 // Volume porosity -> blockage
 inline scalar getPorosity(const dictionary& dict)
 {
-    return 1 - clamp(dict.getOrDefault<scalar>("porosity", 0), 0, 1);
+    return 1 - clamp(dict.getOrDefault<scalar>("porosity", 0), zero_one{});
 }
 
 // Direction porosities -> blockage
@@ -74,7 +74,7 @@ inline vector getPorosities(const dictionary& dict)
     {
         for (scalar& val : blockage)
         {
-            val = 1 - clamp(val, 0, 1);
+            val = 1 - clamp(val, zero_one{});
         }
     }
 

applications/utilities/preProcessing/setAlphaField/setAlphaField.C

@@ -108,7 +108,7 @@ void setAlpha
     {
         cutCell.calcSubCell(cellI, 0.0);
 
-        alpha1[cellI] = clamp(cutCell.VolumeOfFluid(), 0, 1);
+        alpha1[cellI] = clamp(cutCell.VolumeOfFluid(), zero_one{});
 
         if (writeOBJ && (mag(cutCell.faceArea()) >= 1e-14))
         {