Add cylinder data to cylinder model as we record each dive

Add cylinder data to cylinder model as we record each dive

This way the cylinder model list will contain all the different
cylinders that we have ever seen, rather than only containing the models
that we have *edited*.

That makes it much more practical to add new dives with the same
cylinders that we've used before, because now those cylinders will show
up as cylinder models even if we haven't looked and edited the old dives
first.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>