ENH: restart: save/restore cumulative continuity error. See #1172.

applications/solvers/heatTransfer/chtMultiRegionFoam/chtMultiRegionSimpleFoam/fluid/initContinuityErrs.H

+scalar cumulativeContErr = 0;

applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/initContinuityErrs.H

-List<scalar> cumulativeContErr(fluidRegions.size(), Zero);
+PtrList<uniformDimensionedScalarField> cumulativeContErrIO(fluidRegions.size());
+forAll(cumulativeContErrIO, i)
+{
+    #include "setRegionFluidFields.H"
+    cumulativeContErrIO.set
+    (
+        i,
+        new uniformDimensionedScalarField
+        (
+            IOobject
+            (
+                "cumulativeContErr",
+                runTime.timeName(),
+                "uniform",
+                mesh,
+                IOobject::READ_IF_PRESENT,
+                IOobject::AUTO_WRITE
+            ),
+            dimensionedScalar(dimless, Zero)
+        )
+    );
+}
+
+UPtrList<scalar> cumulativeContErr(cumulativeContErrIO.size());
+forAll(cumulativeContErrIO, i)
+{
+    cumulativeContErr.set(i, &cumulativeContErrIO[i].value());
+}