Add TransformationFunction
Add DiseaseConstants
Add some Infection Rates of Train, Car and City
Add Recovery Rate
Add DGL
Add Runge-Kotta
Add Euler
Add SIR
Add calculateSIR()
Add package definitions for function classes
Add some comments
Rename RK2 to ODERK2
Refactor of ODE classes
Add InfectionState IMMUNEM
Add VaccinationFunction
Move SIR functions into own package
Add SIR calculation to SIRFunction$
More changes to SIRFunction
Changing SIR to SIS
Add REAME_FUNCTIONS for explaining the different possible functions