Rewrite clipboard handling so that the clipboard contents won't be freed

Rewrite clipboard handling so that the clipboard contents won't be freed

2004-10-26  Anders Carlsson  <andersca@imendio.com>

	* gtk/gtktextbuffer.c: (gtk_text_buffer_finalize),
	(create_clipboard_contents_buffer), (clipboard_get_contents_cb),
	(clipboard_clear_contents_cb), (cut_or_copy):
	Rewrite clipboard handling so that the clipboard contents won't be
	freed when the text buffer is finalized. Also add clipboard manager support.
	Fixes #95496.