ENH: ensight binary surface output, formatOptions in sampleDict

- For example,
    // optionally define extra controls for the output formats
    formatOptions
    {
        ensight
        {
            format  binary;
        }
    }

These are passed to the writer that support a dictionary of options.
Otherwise the normal null constructor is used.

applications/utilities/postProcessing/sampling/sample/sampleDict

@@ -38,6 +38,16 @@ setFormat raw;
 // but without any values!
 surfaceFormat vtk;
 
+// optionally define extra controls for the output formats
+formatOptions
+{
+    ensight
+    {
+        format  ascii;
+    }
+}
+
+
 // interpolationScheme. choice of
 //      cell          : use cell-centre value only; constant over cells (default)
 //      cellPoint     : use cell-centre and vertex values