Allow special entries in diveplan for available gases

An entry with no time is considered special and not considered when
constructing the profile.

This should allow us to add support for two different ways of adding
information about available gas:

changedepth 0 gasmix
0 0 gasmix @ po2

The first syntax basically says "during the ascent, switch to this gas at
this depth.
The second one says "switch to this gas once the pO2 allows for it"

Neither of these are implemented, yet, but this commit is necessary in
order for the rest of the code to ignore entries with a time field of 0.

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

0 files changed, 0 insertions, 0 deletions