Renamed V0 to V_nominal to use consistent notation.
Replaced nominal with default values as they are computed using the medium default values.
Reverted model back to original version.
Cleaned up code.
Cleaned up code.
Added missing comment.
Replaced V0 with V_nominal.
Corrected use of nominal, start and default suffix.

The previous implementation was not consisent in the use of
state_nominal, state_default and state_start, and derived quantities
such as rho and mu.
Updated section with new packages.