ENH: refine renumberMesh and renumberMethod (addenda to !669)

- provide no_topology() characteristic to avoid triggering potentially
  expensive mesh connectivity calculations when they are not required.

- remove/deprecate unused pointField references from the renumber
  methods. These appear to have crept in from outer similarities
  with decompositionMethod, but have no meaning for renumbering.

- remove/deprecate various unused aggregation renumberings since these
  have been previously replaced by pre-calling calcCellCells, or
  using bandCompression directly.

- make regionFaceOrder for block-wise renumbering optional and
  treat as experimental (ie, default is now disabled).

  The original idea was to sort the intra-region and inter-region faces
  separately. However, this will mostly lead to non-upper triangular
  ordering between regions, which checkMesh and others don't really like.

ENH: add timing information for various renumberMesh stages

ENH: add reset of clockTime and cpuTime increment

- simplifies section-wise timings

ENH: add globalIndex::null() and fieldTypes::processorType conveniences

- provides more central management of these characteristics

applications/test/HashTable4/Test-HashTable4.cxx

@@ -206,7 +206,7 @@ int main(int argc, char *argv[])
             #endif
 
             loopInsert(map, nElem);
-            (void)timer.cpuTimeIncrement();
+            timer.resetCpuTimeIncrement();
 
             unsigned long sum = 0;
             for (label loopi = 0; loopi < nFind*nLoops; ++loopi)
@@ -268,7 +268,7 @@ int main(int argc, char *argv[])
             HashSet<label, Hash<label>> map(32);
 
             loopInsert(map, nElem);
-            (void)timer.cpuTimeIncrement();
+            timer.resetCpuTimeIncrement();
 
             unsigned long sum = 0;
             for (label loopi = 0; loopi < nFind*nLoops; ++loopi)

applications/test/nullObject/Make/files

@@ -1,3 +1,3 @@
-Test-nullObject.C
+Test-nullObject.cxx
 
 EXE = $(FOAM_USER_APPBIN)/Test-nullObject

applications/test/nullObject/Test-nullObject.cxx

@@ -37,6 +37,7 @@ Description
 #include "HashSet.H"
 #include "faceList.H"
 #include "pointField.H"
+#include "globalIndex.H"
 #include "IOstreams.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -150,6 +151,18 @@ int main()
     NullObject::nullObject = "hello world";
     NullObject::nullObject = Foam::identity(5);
 
+
+    {
+        const auto& gi = globalIndex::null();
+        Info<< "globalIndex::null() => "
+            << " empty: " << gi.empty()
+            << " nProcs: " << gi.nProcs()
+            << " total-size: " << gi.totalSize() << nl;
+
+        // Even this works
+        Info<< "   offsets: " << gi.offsets() << nl;
+    }
+
     Info<< nl;
 
     return 0;