ODE MSEIRS4 normalize infection transition

[HenrZu]

Bug description

Adaptive stepper was forced to tiny time steps because infection terms used absolute counts (beta * I_total * S ) instead of per-capita force. Normalize force of infection by total population so step sizes stay reasonable.

THis also leads to a lot of logging (since the output is printed) in the example.

Version

Any

To reproduce

run example and see output

Relevant log output

Add any relevant information, e.g. used compiler, screenshots.

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project