- they looks correctly visually, we can make then connector shapes
   once we have new implementation

Seems our Zip package is a bit too strict in checking archive
consistency - surely writing it out correctly is good, but rejecting
otherwise fine odf is not.

This reverts commit cd105c5a.
We can't use gb_Library_add_objcxxobjects here because
gb_ObjCxxObject_get_source has .mm suffix

To activate the layout and node dumping features in sw, set the SW_DEBUG
environement variable to anything before running the office. F12 will
then dump the layout as a layout.xml file in the working directory, and
Shift+F12 will dump the nodes structure as nodes.xml at the same place.