This patch is the continuation of my work of adding support for x error bars, this patch implements importing the bars from ODF format but there's still one case that don't seem to work right, when you import error bars to other applications besides calc that use their own data provider. It seems it don't loads the data correctly into the data provider and all the X columns seems like linked together (if i change one the other change too), i tried a lot of ideas and looked at how other code handle it but i cant seem to get it work, if you could check it out and fix it or tell me whats wrong, that would be highly appreciated. It would be awesome to get this working for 3.6 release since its a really desired feature. Another current issue is when you select the chart, the x error bars columns don't get highlighted like the rest.