Added examples for File and Timer.

src/Examples/FileExample.cpp

+#include <iostream>
+#include <TNL/File.h>
+#include <TNL/String.h>
+
+using namespace TNL;
+using namespace std;
+       
+int main()
+{
+    File file;
+
+    file.open( String("new-file.tnl"), IOMode::write );
+    String title("Header");
+    file.write( title );
+    file.close();
+
+    file.open( String("new-file.tnl"), IOMode::read );
+    String title2;
+    file.read( title2, 4);
+    file.close();
+
+    if fileExists( "new-file.tnl" )
+         std::remove( "new-file.tnl" );
+}
+

src/Examples/TimerExample.cpp

+#include <iostream>
+#include <TNL/Timer.h>
+
+using namespace TNL;
+using namespace std;
+       
+int main()
+{
+    Timer time;
+    time.start();
+    time.stop();
+    time.getRealTime();
+    time.reset();
+}
+