Dynamic modelling improvements

by Ksenija Bestuzheva for ASCEND

The goal of the project is to add new syntax for derivatives which will improve the capabilities of ASCEND in dynamic modelling and increase usability. Corresponding changes to the solver API would need to be made. This work should be done in such a way so that in future adding the support for processing partial and higher order derivatives would be possible and would build on the changes made within the bounds of this project.