Lowered logging level of running MacroModel messages
Fixed missing data extracted from simplex after error.

If simplex encounters an error (in some circumstances, it actually
should raise an error), loop takes the best force field simplex
generated thus far. Previously, it incorrectly copied the method
attribute.
Fixed logging of original / modified step size
Fixed IndexError that originated from differentiation of parameters.

When a parameter goes to an unallowed negative value during
differentiation, the step size is scaled to prevent such an error
from occuring. However, the error handling was done incorrectly,
such that even the bad parameter sets were included with the good
differentiated parameter sets.
Minor change to simplex.

If the simplex optimizer is working with very similar paramter
sets (perhaps the simplex has contracted many times and the
parameter sets are numerically equivalent) or even different
parameter sets that happen to all produce the same objective
function value, then in the weighted inversion scheme, a
ZeroDivisionError will be raised. Added error handling for
this.