Add new cylinder models to the cylinder model store

Add new cylinder models to the cylinder model store

We also need to actually fill the model store with the cylinder models
we have in our dive lists to begin with.

This makes it all *trivial* to add a new cylinder model: just use a new
description, fill in the size and working pressure, and you're done.
The type automatically gets filled in, unless that description already
existed (in which case we leave it alone).

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