ENH: improved handling for clamping

- proper component-wise clamping for MinMax clamp().

- construct clampOp from components

- propagate clamp() method from GeometricField to FieldField and Field

- clamp_min() and clamp_max() for one-sided clamping,
  as explicit alternative to min/max free functions which can
  be less intuitive and often involve additional field copies.

- top-level checks to skip applying invalid min/max ranges
  and bypass the internal checks of MinMax::clamp() etc.

applications/utilities/preProcessing/PDR/pdrFields/PDRarraysCalc.C

@@ -1279,7 +1279,7 @@ void write_scalarField
             continue;
         }
 
-        os << limits.clip(fld(cellIdx)) << nl;
+        os << limits.clamp(fld(cellIdx)) << nl;
     }
 
     os << token::END_LIST << token::END_STATEMENT << nl;

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

@@ -58,12 +58,11 @@ namespace Foam
 {
 
 // Read porosity, change to blockage. Clamp values [0-1] silently
-static const scalarMinMax limits01(scalarMinMax::zero_one());
 
 // Volume porosity -> blockage
 inline scalar getPorosity(const dictionary& dict)
 {
-    return 1 - limits01.clip(dict.getOrDefault<scalar>("porosity", 0));
+    return 1 - clamp(dict.getOrDefault<scalar>("porosity", 0), 0, 1);
 }
 
 // Direction porosities -> blockage
@@ -75,7 +74,7 @@ inline vector getPorosities(const dictionary& dict)
     {
         for (scalar& val : blockage)
         {
-            val = 1 - limits01.clip(val);
+            val = 1 - clamp(val, 0, 1);
         }
     }