STYLE: simplify short-circuit involving autoPtr (#1775)

- with '&&' conditions, often better to check for non-null autoPtr
  first (it is cheap)

- check as bool instead of valid() method for cleaner code, especially
  when the wrapped item itself has a valid/empty or good.
  Also when handling multiple checks.

  Now
      if (ptr && ptr->valid())
      if (ptr1 || ptr2)

  instead
      if (ptr.valid() && ptr->valid())
      if (ptr1.valid() || ptr2.valid())

applications/utilities/surface/surfaceFeatureExtract/surfaceFeatureExtract.C

@@ -346,14 +346,14 @@ int main(int argc, char *argv[])
 
         // Load a single file, or load and combine multiple selected files
         autoPtr<triSurface> surfPtr = loader.load(loadingOption, scaleFactor);
-        if (!surfPtr.valid() || surfPtr().empty())
+        if (!surfPtr || surfPtr->empty())
         {
             FatalErrorInFunction
                 << "Problem loading surface(s) for entry: "
                 << dictName << exit(FatalError);
         }
 
-        triSurface surf = surfPtr();
+        triSurface surf = *surfPtr;
 
         Info<< nl
             << "Statistics:" << nl;