Save button on menu calls InfoWidget save

When editing a dive and clicking save button on menu bar, it saved
dive information but didn't mark dive as not being edited anymore.
For closing file, user should always click on the save button on
the bottom of the page and then saving it.
Now when clicking save button on menu bar, it will call the
accept_changes before saving to disk.

Signed-off-by: exhora <exhora.tat@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>