SubscriptionManager.ScoresSubscription: Implement new
getSynchronization() interface

See 1e6bc5520a749c84f9df4e87ce3849043aa573f3 and
ec2af8e5abc734a3279462f839c20014197c608e
SubscriptionManager.Subscription: Get rid of
synchronizeSubscriberByFCP()

- The special case of sending the Identity/Trust/Score objects in bulk
there was  replaced by the mechanism of
storeSynchronizationWithoutCommit(): It stores the synchronization as a
series of regular ObjectChangedNotifcation, which can be deployed by the
regular notifySubscriberByFCP().
- Consequently, the parts of the JavaDoc which were better than at
notifySubscriberByFCP() are moved to that one.
- What remains is adapting notifySubscriberByFCP() to be able to also
deploy the special BeginSynchronizationNotification and
EndSynchronizationNotification. They are rather simple, so they didn't
justify keeping the synchronizeSubscriberByFCP() to contain them.
SubscriptionManager.storeNewSubscriptionAndCommit(): Fix doing database
modifications outside of a transaction

- It previously was assumed that this function would not have to be
called while taking the database lock: All modifications to the database
it did were inside of Subscription.storeAndCommit(), so it was enough
that that function did take care of doing a transaction. But recently
storeNewSubscriptionAndCommit() was changed to call
Subscription.storeSynchronizationWithoutCommit(), which does modify the
database. So now the caller of the storeNewSubscriptionAndCommit() must
take sure to lock the database.
- The JavaDoc is fixed to mention the above.
- The function is renamed from "...AndCommit()" to "...WithoutCommit()"
to stress that outside transaction management is needed. The committing
is removed from the function of course.
- The Subscription.storeAndCommit() is removed since it is not used
anymore.
- The callers are fixed to do transaction management.