Core changes to effectively make the synchronization an autonomous feature

Make the changes in the framework to handle the case when the sync is disabled. There will be tricky issues because Direct Edit and Direct Transfer need some logic that is shared by the synchronization.

Notes:

• No GUI changes are expected in that ticket.
• When the app starts, if former version was < 5.2.0, then turn on the synchronization by default (the former mechanism will still override).