Change the format of JSON transfered for pedigree or fanchart.
 The new format makes it possible to send multiple generations for
 children, and avoids duplicating person information (in particular
 when we have implex, or if we want to send information about the
 children of some ancestors later on to display more info in the tree)
Display multiple generations of children in pedigree
Do not reconnect the settings callbacks whenever we refresh them,
 since otherwise we end up doing more and more recomputations of the
 layout.