Non-deterministic code generation

[dweindl]

For my current model, the order of state variables changes between subsequent imports.
Not a big issue, but something we'd like to avoid.

[dweindl]

Possible that the change was related to different toposort after #2234 .
Couldn't reproduce with the same current amici version. Closing.

[dweindl]

Found it. Processing of event assignments.