pyroptosis model (Sara and Fiona)

integrate single cell response (ODE) with PhysiCell

Pyroptosis version 1

Sara&Fiona: We have added the first pyroptosis code. We have edited config/PhysiCell_settings.xml and custom_modules/internal_viral_response.cpp. Fow a quick overview: See rows 377-429 (commented out), rows 430-471 and rows 847-849 in the xml-file. See rows 54-72 (commented out) and rows 129-end in the cpp-file.