Separate the notion of creating the cylinder widgets from showing them

Now we always create the MAX_CYLINDER sets of cylinder widgets.  But we
don't actually pack them into the frame - that's a separate phase.

Right now we still do the stupid "always just pack two cylinders" thing,
but the idea is that we can pack just as many as the dive needs on a
per-dive basis.

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