title: how to perform boost::filesystem copy_file with overwrite
body: <p>The Windows API function <code>CopyFile</code> has an argument <code>BOOL bFailIfExists</code> that allows you to control whether or not you want to overwrite the target file if it exists. </p>
  
  <p>The <code>boost::filesystem</code> <code>copy_file</code> function has no such argument, and will fail if the target file exists. Is there an elegant way to use the boost copy_file function and overwrite the target file? Or is it better to simply use the Windows API? My current target platform is Windows, but I prefer to use STL and boost where possible to keep my code platform independent. </p>
  
  <p>Thank you.</p>