Connect cylinders entered in planner with the gases available

Now the gases for which we have cylinders are offered in the gas selection
list and correctly recognized and added for the plan.

Still tons of work to be done to make this work the way it is designed,
but we are getting closer.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
When entering a new point, pick the previous gas by default

This is much more useful than always picking air.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add depth colum to cylinder model

To make the planner work this adds a new column to the Cylinder widget
(depth - for the depth at which we want to change to a certain gas
during deco).

This also tries to hide that column in the equipment view and hide the
start/end pressure columns in the planner view. Oddly that fails :-(

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Make planner work again

This partially reverts changes in commit 1b655d5c806b ("Correctly track
gases when manually adding and then editing dives") as it turns out this
did NOT help us correctly track gases (which is ironic, given the title of
that commit). I didn't actually want to revert that commit as
infrastructure has changed since then and this made the patches look even
more incomprehensible.

So we are back to tracking the "gas on which we arrive at this spot" in
each dive plan node as this makes the rest of our planning so much easier
- I had forgotten about the reasons why we did things this way when I made
the above mentioned commit.

Instead we now make sure that our available tanks are added the correct
way, that such entries are ignored when planning and when drawing the
editable profile, and that at the end it all gets assembled correctly.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Remove some debug output

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
First steps to make add dive work with the correct infrastructure

This just makes sure that we do the right thing with the staging drive,
that we don't mess up the selection, the we are smart about using our
helper functions, etc.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Handle add dive cancel correctly

This should leave the program in a consistent state after add dive was
cancelled (and do the right thing in case the dive list was empty).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Use existing helper function

And remove spurious extra ';'

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Make gas selection for add dive work

This now offers the correct gases for which we have cylinders defined.

For both the planner and add dive we still don't end up with the correct
cylinders in the resulting dive. But that's for another commit to fix.

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