Replace data/inputs/diamond.cti with test_problems version that has
more information. This results in a change in the default pressure and
mole fractions of the gas phase, which in turn changes the result of
one of the regression tests. This is fixed by setting the composition
and pressure of the gas phase in the test to their original values. The
default state from the CTI file matches from the paper.
In addition, there was a difference in the reversibility of reaction u
between the files. Since the thermo for C(d) specifies that the
reaction is irreversible, this is the sense of the reaction that is
chosen.
Include plotting in the diamond_cvd.py and use open properly.
