Improve ODF roundtrip of conditional formats. [#726201]

2014-03-17  Andreas J. Guelzow <aguelzow@pyrshep.ca>

	* openoffice-write.c (odf_write_style_cell_properties): even write
	pattern and background colour for pattern 0
	* openoffice-read.c (oo_style_prop_cell): set pattern and background
	colour even for pattern 0