Gas usage + Show after last page of decoplan. + Units in 0.1 litters (or bars), hence 16bits. + Define CF#56 and CF#57, defaults to 20.0 l/min. + Go RED if volume > 6553.5 (saturated). + Calculate gas usage at bottom of ascent (safe bet). + Fix when first gas is not Gas1. + BUGFIX gas usage: first gas is not in the sorted gaslist (in general). KNOWN BUG: wrong result if the gaslist is not sorted, or first gas do have a depth > 0.