Keep last open dives directory

Last open dives directory is stored in settings, so no need to walk through all
subdirectories all the time.

Signed-off-by: Helio Chissini de Castro <helio@kde.org>
Ticket 127 - Repopulate context menu on preferences change

Ticket 127 mention that context menu is fixed on imperial mode, which is
partial true. Context menu only not have the changes on header model updated
when preferences are chenges during execution. Hard to note because if
program is closed and opened again, the context is initialized properly.
Since actions aren't bound to the header model, we need iteract of current
items and change the title.

Signed-off-by: Helio Chissini de Castro <helio@kde.org>
Merge branch 'fileopen' of github.com:heliocastro/subsurface