OSspecific: altered file tests

- removed the previously added fileName type(), isDir(), isFile() methods.

- added optional bool parameter to isFile() function to explicitly
  enable/disable the check for gzip files.

- fixed minor bugginess where the default usage of isFile() would result in
  false positive matches.

- be slightly more stringent and use isDir() and isFile() instead of
  exists() function when we actually know the expected type.

src/OpenFOAM/primitives/strings/fileName/fileName.C

@@ -55,24 +55,6 @@ Foam::fileName::Type Foam::fileName::type() const
 }
 
 
-bool Foam::fileName::exists() const
-{
-    return ::Foam::exists(*this);
-}
-
-
-bool Foam::fileName::isDir() const
-{
-    return ::Foam::isDir(*this);
-}
-
-
-bool Foam::fileName::isFile() const
-{
-    return ::Foam::isFile(*this);
-}
-
-
 //  Return file name (part beyond last /)
 //
 //  behaviour compared to /usr/bin/basename:

src/OpenFOAM/primitives/strings/fileName/fileName.H

@@ -134,15 +134,6 @@ public:
             //- Return the file type: FILE, DIRECTORY or UNDEFINED
             Type type() const;
 
-            //- Does it exist (as FILE or DIRECTORY) in the file system?
-            bool exists() const;
-
-            //- Does it exist as DIRECTORY in the file system?
-            bool isDir() const;
-
-            //- Does it exist as FILE in the file system?
-            bool isFile() const;
-
         // Decomposition
 
             //- Return file name (part beyond last /)