Do not add unnecessary / at end of location on divelogs import

The check if both location and site exist was flawed causing an extra
slash on location name when the SITE was empty. Thus resulting in
multiple location candidates when exporting to divelogs.de and
re-importing to Subsurface.

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix "Select tags" dialog behavior

* Apply filter only when OK button pressed
* Restore tags selection from dive mask when Cancel button pressed
* Fix selection logic when selected or all dives are filtered out (hide
  profile, tooltips, etc.)

Not sure whether call to repaint_dive() is required.

Signed-off-by: Sergey Starosek <sergey.starosek@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix yet another selection issue

If we manually deselect dives without changing Gtk's notion of what is
selected and then want to simply recreate the dive list, Gtk re-selects
the unselected dives in the process of clearing out the dive list. How
very strange.

Also, after making changes to the selection we need to make sure that we
update the stats.

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