- remove no necessary packages (DiffererntialEquations.jl and so on, which are
reexported by GasChromatographySimulator)
- repair the Pluto-notebook, which was copied from VGGC, and does not relate the
functions of the GasChromatographySystems package correctly and uses obsolete
functions from GasChromatographySimulator (gf_exp() for example)