CCR patch: Create memory space to store cylinder pressures

This patch creates memory space to store both the cylinder pressure of the
diluent cylinder as well as the oxygen partial pressures of up to four
oxygen sensors. This is accomplished within profile.h
1) To the plot_data structure, add:
   a) an array diluentpressure[2] to store diluent pressures
   b) create o2setpoint and o2sensor[4] to store oxygen partial pressures
2) Define a constant and prototypes to access the cylinder pressures
   and their corresponding interpolated values.

Signed-off-by: willem ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
DiveList: don't save default column width

This is an elegant way around our problem with people who have the
horrible old "100px" column width in their settings. The first time they
run Subsurface after this fix things won't get better, but the offending
keys will be deleted at exit. And the second time they run, they'll get
the much more sensible new default widths.

Thanks to Thiago for this idea.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
TableWidgets: change default column width and don't save unchanged widths

Similar change to the dive list. The idea is to not save things that are
the default. This way Subsurface will do the right thing when defaults
change.

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

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