Add support for parameter estimation

[agarny]

An important component of model development is parameter estimation. It would therefore be nice to have a way to do parameter estimation in libOpenCOR. For this, we would need a C++ library so that both the C++ and the Python version of libOpenCOR can support parameter estimation out of the box. A possible candidate could be PEST++. Another obvious candidate is CVODES, which is already used although not its sensitivity component.