Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
With that also begin reworking the internal structure of the simulation
model storage. Some models have parameter information extracted from
Ngspice, which was specially patched to faciliate that. The model is
stored and managed by the SPICE_MODEL class (later will be renamed to
SIM_MODEL).
