tutorials: Renamed .org -> .orig

See http://www.openfoam.org/mantisbt/view.php?id=2076
  - .org is the file extension for emacs org-mode as well
  - .orig is more to the point (.org isn't always recognized as "original")
  - .original is too long, although more consistent with the convention
    of source code file naming

Update script contributed by Bruno Santos

tutorials/basic/potentialFoam/pitzDaily/0.orig/U

@@ -0,0 +1,50 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  dev                                   |
+|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volVectorField;
+    object      U;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+dimensions      [0 1 -1 0 0 0 0];
+
+internalField   uniform (0 0 0);
+
+boundaryField
+{
+    inlet
+    {
+        type            fixedValue;
+        value           uniform (10 0 0);
+    }
+
+    outlet
+    {
+        type            zeroGradient;
+    }
+
+    upperWall
+    {
+        type            noSlip;
+    }
+
+    lowerWall
+    {
+        type            noSlip;
+    }
+
+    frontAndBack
+    {
+        type            empty;
+    }
+}
+
+// ************************************************************************* //