* fhandler_clipboard.cc (fhandler_dev_clipboard::fhandler_dev_clipboard):
Initialize new fields. Open clipboard here.
(fhandler_dev_clipboard::dup): New method.
(fhandler_dev_clipboard::open): Accomodate new fields. Register clipboard
here, if appropriate.
(set_clipboard): New function. Moves buffer to clipboard.
(fhandler_dev_clipboard::write): Truly implement clipboard writing.
(fhandler_dev_clipboard::read): Reimplement to allow successive reads.
(fhandler_dev_clipboard::lseek): Truly implement seeks in clipboard.
(fhandler_dev_clipboard::close): Clear out new fields. Support sequential
reads and sequential writes. Support for binary data via a native clipboard
format.
