ENH: Add null constructor to PointHit

src/OpenFOAM/meshes/primitiveShapes/objectHit/PointHit.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2013 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -81,6 +81,15 @@ public:
 
     // Constructors
 
+        //- Construct null
+        PointHit()
+        :
+            hit_(false),
+            hitPoint_(vector::zero),
+            distance_(GREAT),
+            eligibleMiss_(false)
+        {}
+
         //- Construct from components
         PointHit
         (