[evol] organized_data: added ignored attributes
[evol] attributes parameters rework §3 (schema + defaults) (refs #142)
[fix/evol] correct a bug in the item creation when handling the parent parameter, allow specifying a default parent per object, and provides a new find_by_full_handle() handy method
[evol] limit parent location/type for item creation (not yet properly integrated)
[cleanup] reorganized config
[fix] corrected object default config
[evol] added default config and simplified MilkyPond shadow config (and minor other changes)