Use 2.5.0a2 (git hash 471041a2) to run the examples. Update some
formatting in comments and docstrings. Move imports to the top of
Notebooks. Set the matplotlib magic before importing matplotlib.
Fix deprecation warnings from Pandas about argmax and set_value.
The original figure labeled the y-axis as plotting mole fractions of OH. But this was a value obtained from get_state() and hence should be mass-fractions.
