Remember non-expanded state in 'remember_tree_state()' too

The 'remember_tree_state()' thing is meant to remember if a dive trip is
expanded or not, but it missed the "or not" part.  IOW, it never cleared
the expanded flag, it only ever set it.

As a result, if you were doing multiple operations on the divelist tree
(testing all the recent gtk-model removal, for example) the dive trips
would end up expanding more and more, even if you collapsed things by
hand in between operations.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>