Logics for simulation and analysis

For performing a simulation with a certain model, one or more Runner classes are provided. Upon instantiation, a Runner object is given a Model object. It then provides a run method which can be invoked to run the model for a certain model time interval and which returns a data structure containing the results of the run. The latter results consist of time-series of certain requested variables for all entities and process taxa that can then be used to analyse or plot the results.