Show tank / nitrox / air consumption information in the info_frame
Even though we go down to an 8pt font the info_frame changes size when the
air info is added. I don't like this but want to see how Linus would like
this resolved before going overboard.
Minor tweaks to the formating (we don't need two decimals when printing
the liters of air consumed).
This patch does NOT remove the plot of the air information in the profile
graph. I think we want to remove that once we like the text where it is,
but I wanted to do one thing at a time.