Move visibility Star widget to the DiveNotes tab

This looks much better and seems much more contextual.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Integrate visibility Star widget into editing flow

This also removes some incorrect code from the clear() function for the
DiveInfo tab. Putting the readOnly() calls for the DiveNotes tab there was
wrong.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>