I have updated the Donlon data set to AIXM 5.1.1 and created a pull request (#28). Github just allowed me to create the pull request for merging the solitec:aixm-511 branch into the aixm:master branch.
As the community might be interested in having the Donlon data set available in both versions (5.1 and 5.1.1), we should probably have two branches. What do you think?