Require libgnomeprint >= 2.5.1. Thanks to Colin Slater

Require libgnomeprint >= 2.5.1. Thanks to Colin Slater

	* configure.ac:

	Require libgnomeprint >= 2.5.1. Thanks to Colin Slater
	<kiltedaco@gmail.com>

	* djvu/djvu-document.c: (djvu_document_get_orientation),
	(djvu_document_set_orientation), (djvu_document_get_page_size),
	(rotate_pixbuf), (djvu_document_render_pixbuf),
	(djvu_document_document_iface_init):
	* dvi/dvi-document.c: (dvi_document_get_orientation),
	(dvi_document_set_orientation), (dvi_document_get_page_size),
	(rotate_pixbuf), (dvi_document_render_pixbuf),
	(dvi_document_document_iface_init):

	Dvi and djvu backends are ported to new API