[GSoC] Formula Editor Lists

https://jenkins.catrob.at/job/Catroid-Multi-Job-Custom-Branch/2442/
I had to introduce a new XStreamAlias called "data", but XStream mixed up the order of the XML Structure, when I used this name, so I had to change it to "xdata" in order to get it on the right position, right after the tags "header" and "objectList". I could not figure out, how to fix this problem of tag - ordering, by using XStream commands. Is there a better solution for this problem?