Initialization of compartments depends on their order in the model

[SergeStinckwich]

When you want to initialize compartment's model in a scenario, you need to know the order of their definition in the model. This is really error-prone.

Example in this model:

KModel MultiSpecies
    attribute: #(species -> humans birds).

Composition Influenza
    model: 'SEIRS';
    model: 'MultiSpecies'.

Scenario Scr1
    on: 'Influenza';
    mu_species: #(0.000365 0.00137);
    beta_species: #(#(0 0.21) #(0 0.42));
    gamma_species: #(0.25 0.233);
    sigma_species: #(0.5 0.67);
    nu: 0.00274;
    lambda: #(beta*I/N sum);
    N: #(species);
    S_species: #(500 4990);
    I_species: #(0 10).

mu_species: #(0.000365 0.00137); initialization depends on the order of species defined in MultiSpecies concern.