Improve chart roundtrip through ODF. [#728197]

2014-04-17  Andreas J. Guelzow <aguelzow@pyrshep.ca>

	* openoffice-read.c (odf_apply_style_props): read both
	svg:stroke-width and gnm:stroke-width
	* openoffice-write.c (od_style_prop_chart): write gnm:stroke-width
	to remember line-widhts of 0.