The address of the HelperServer is now calculated when the class
is initialized.

Cache is not useful in the context of the present application.

If some settings are added though the GUI, the client will
save them on exit.

The mechanism is based on syncing message consumption, which works
only while the client is syncing (therefore, not in paused mode).

When GUI consumes a "SyncMessage", an "unsynced" counter is
increased, while a "AckSyncMessage" causes a "synced" counter to
increase. The two counters are pushed to GUI regularly enough.