Remove redundant temperature readings

Remove redundant temperature readings

I'm aiming to really differentiate in dive log software by making my XML
export files be *clean*, dammit.

That means that we don't have random names, we don't have crazy random
units, and we don't have redundant information.

So when the temperature doesn't change, just don't report it.  That's
already what "no sample" means, just clean things up.

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