This makes it MUCH easier to deal with a lot of dives.
Instead of needing a more complicated model we simply use the meta data that
allows us to create the dive trip sections to hide (make invisible + height 0)
all dives that aren't in the selected trip.
I'll admit that this was much easier than I expected it to be.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
83c72e7a79