treemodel.cpp
2009-03-23 still working on insert/remove of rows
2009-03-06 Iteration over map works now (again)
2009-02-04 started to rewrite first(), next()
2008-10-29 subtrees can be deleted now
2008-10-06 Various fixes, also from 1.12. branch
2008-08-05 Preview: Added QTreeView to mainwindow (not yet functional)