consistency update for null pointers

- uniform use of reinterpret_cast<foo*>(0) instead of
  reinterpret_cast<foo*>(NULL)

- make all static null() members inline since they are really only a cast:
      "*reinterpret_cast<foo*>(0)"

applications/utilities/parallelProcessing/decomposePar/domainDecomposition.C

@@ -299,7 +299,7 @@ bool domainDecomposition::writeDecomposition()
         (
             curPatchSizes.size()
           + curProcessorPatchSizes.size(),
-            reinterpret_cast<polyPatch*>(NULL)
+            reinterpret_cast<polyPatch*>(0)
         );
 
         label nPatches = 0;