From Martin Naylor, replace osgDB::fstream with an osgDB::open() call.

include/osgDB/fstream

@@ -19,26 +19,17 @@
 
 #include <fstream>
 
+
 namespace osgDB
 {
 
 /**
-* Replacements for std::fstream, std::ifstream, and std::ofstream to
+* Convenience function for fstream open , std::ifstream, and std::ofstream to
 * automatically handle UTF-8 to UTF-16 filename conversion. Always use one
 * of these classes in any OpenSceneGraph code instead of the STL equivalent.
 */
 
-class OSGDB_EXPORT fstream : public std::fstream
-{
-public:
-    fstream();
-    explicit fstream(const char* filename,
-        std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out);
-    ~fstream();
-
-    void open(const char* filename,
-        std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out);
-};
+void OSGDB_EXPORT open(std::fstream& fs, const char* filename,std::ios_base::openmode mode);
 
 class OSGDB_EXPORT ifstream : public std::ifstream
 {