Use the root-finding feature of CVODES

[Yuri05]

Required for the better handling of "hidden" discontinuities and events with a-priory unknown starting point.

E.g. in the attached example 11_Human_SingleORAL_Weibull.zip concentration in some luminal compartments slightly changes when reducing the maximal step of the ODE solver.
This is due to the discontinuity in the tablet location (Weibull dissolution with Use As Suspension = false - meaning the tablet "jumps" from one GI-Segment to the next one. Those jumps are not explicitly handled by the solver).

S. also Open-Systems-Pharmacology/MoBi#321

https://sundials.readthedocs.io/en/latest/cvode/Mathematics_link.html#rootfinding
https://computing.llnl.gov/projects/sundials/usage-notes
https://sundials.readthedocs.io/en/latest/cvode/Usage/index.html#cvode-usage-cc-cvrootinit
https://sundials.readthedocs.io/en/latest/cvode/Usage/index.html#cvode-usage-cc-optional-input-optin-root