Extend SEIRModel

[DavAug]

• [x] Remove ForwardModel base class
• [x] Let SEIRModel inherit from pints.ForwardModel
• [x] Init assigns default output_names, n_output, n_parameters
• [x] implement n_outputs and n_parameters according to pints.ForwardModel
• [x] implement set_outputs which can be used to select any subset of outputs (S, E, I, R or n_incidences)
• [x] implement output_names which returns the output names (selected outputs)
• [x] Refactor simulate to return set outputs only and remove flag return_incidences

[FarmHJ]

68 Completed