Save cylinder O2/He content after the cylinder type description

Save cylinder O2/He content after the cylinder type description

This changes the save format xml to be a bit more readable: instead of
putting the gasmix first, put the cylinder type (size, workpressure and
description) first, then gasmix, then pressure details.

It makes no difference for machine parsing, but I think it's a lot more
logical for humans that actually look at the xml file.  And we really do
want to make the xml file readable by humans.

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