ENH: add input surface scaling (issue #514)

- surfaceFeatureExtract
  * dictionary "scale" entry

- triSurface
- triSurfaceLoader
  * optional scaleFactor on reading

- surfaceAdd
- surfaceBooleanFeatures
- surfaceClean
- surfaceCoarsen
  * scale option

- surfaceTransformPoints, transformPoints
  * scale option as scalar or vector quantity

src/conversion/common/writer/meshWriter.H

@@ -125,7 +125,8 @@ public:
 
     // Constructors
 
-        //- Create a writer object with given output scaling
+        //- Create a writer object with given output scaling.
+        //  Treats a zero or negative scale factor as unity scaling.
         meshWriter
         (
             const polyMesh&,

src/conversion/fire/FIREMeshWriter.H

@@ -97,7 +97,8 @@ public:
 
     // Constructors
 
-        //- Prepare for writing, optionally with scaling
+        //- Prepare for writing, optionally with scaling.
+        //  Treats a zero or negative scale factor as unity scaling.
         FIREMeshWriter(const polyMesh&, const scalar scaleFactor = 1.0);