Features worth moving to ospsuite-R

[Yuri05]

I think esqlabsR contains some features which are of common interest and not just ESQLabs-specific.
Those features could/should be moved to the ospsuite-R

• Steady state calculation/export (compare discussions in Mobi or R : How to transfer values of all state variables of a system at steady state to the simulation Open-Systems-Pharmacology/Forum#1450)
• Sensitivity plots (https://esqlabs.github.io/esqlabsR/articles/esqlabsR-sensitivity.html ; s. also discussions in About sensitivity analysis output Open-Systems-Pharmacology/Forum#1541)
• ...