"add dive" testing

[Dirk Hohndel]

OK, I finally finished my hacking on "add dive" (famous last words).

I guess I should instead claim that I have run out of ideas how to break
things.

The way it's supposed to work now is like this:

The cylinders in the Equipment tab are the cylinders available for the
dive that is being added. So if you change the cylinder (e.g., change
the fO2) then the gas for the different segments changes. Similarly, if
you add a cylinder with a different gas, then that gas becomes available
to be used during a segment of the dive.
And of course you can no longer delete a cylinder that provides a gas
that is needed for the dive.

Please play with this and show me your creative ways of breaking it :-)
Oh, and if you think that this is completely bogus and wrong, let me
know, too!

Similar changes need to happen to the dive planning function, but I'm
running out of time for tonight, so I'll tackle that tomorrow.

Thanks

/D