ENH: improve volRegion handling of moving meshes (#1194)

- implemented as lazy evaluation with an additional update() method.
  This avoids unnecessary changes until the values are actually
  required.

- apply mesh motion changes for momentum, volFieldValue,
  specieReactionRates function objects

tutorials/combustion/XiEngineFoam/kivaTest/system/controlDict

@@ -75,6 +75,8 @@ functions
             }
         #};
     }
+
+    #include "momentum"
 }
 
 // ************************************************************************* //

tutorials/combustion/XiEngineFoam/kivaTest/system/momentum

@@ -0,0 +1,33 @@
+// -*- C++ -*-
+// Calculate momentum fields
+momentum
+{
+    type    momentum;
+    libs    ("libfieldFunctionObjects.so");
+    log     true;
+
+    writeControl    writeTime;
+    // executeInterval 10;
+
+    // writeToFile     true;
+
+    writeMomentum   true;
+    writePosition   true;
+    writeVelocity   true;
+
+    // Cells to select (all/cellSet/cellZone)
+    regionType  all;
+    // name     c0;
+
+    cylindrical false;
+
+    origin  (0 0 0);
+    rotation
+    {
+        type cylindrical;
+        axis (1 0 0);   //< local Z
+    }
+}
+
+
+// ************************************************************************* //