Remove the tissue_tolerated_ambient_pressure[] array

It wasn't really used.  The only reader of that array was the same thing
that wrote the entry, so instead of storing it in the array (and never
using it ever after), just use the calculation directly, and remove the
array entirely.

This makes it much easier to see that the gradient factors are not used
for any long-term state.  We use them only for the pressure tolerance
calculations at that particular point, and there is no "history"
associated with it.

This matters mainly because it means that we can do all the deco
initialization and setup without worrying about exactly which gradient
factors we will use.  And we can use different gradient factors for
diving and planning and no-fly calculations without the GF choice
affecting the tissue state.

Acked-by: Robert C. Helling <helling@lmu.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add a more stronly worded warning / disclaimer for dive planning

This is a late string change, but I think this may be a valid exception of
the string freeze...

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>