[BUG] Default sorting order and deleting a trip, while switching sorting orders

[Lubomir I. Ivanov]

just noticed a couple of things, which might have been lurking for
quite some time.
(current master = cb490b7abf285)

1) (more of a nitpick) the default sorting order in the divelog isn't
correctly indicated when the app. is first started.

if you run subsurface and then click on the divelist column titles
(e.g. "location") you get a little arrow which indicates an ascending
or descending order for that column data.
same arrow is not shown when first started and the user does not know
that the divelist is actually sorted by "#" (i remember it was
by "date" at some point).

i've tried a brief google search for that, but wasn't able to find any
info if GTK allows it.

2) there is strange bug if you do the following:

- ./subsurface ./dives/*
- log menu -> enable "autogroup"
- click on the "location" column title
- now click back on the "#" column title
(the test dives should be packed into 4 trips at this point)
- right click on the trip with 15 dives and "delete trip" it
- only one dive pops out after the trip is deleted
(should happen for all trips)

i can try taking a closer look later tonight, but it may be time for
me to figure out what is actually happening.

lubomir
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