Fix for debian
Fix: [ bug #1618 ] PHP Error thrown when saving a barcode
id_parent and id_children was not set.
So introduce new method to return same with no risk to break current
working code to address this.
Merge remote-tracking branch 'origin/3.6' into develop

Conflicts:
	htdocs/product/fiche.php
	htdocs/user/class/user.class.php