[PATCH] File class documentation hidden by ftools.rb

Hello,

"ri File" gives the documentation from lib/ftools.rb and not the intended
description of the File class.

ftools.rb has a declaration of the File class, which I suppose is not
needed, so I removed it (attached patch). This fixes the documentation
issues.

All 1.8 branches are affected. trunk is not (ftools.rb was removed).

Regards,
Lars