- adding parameters: grass_regrowth_time
- reordering of arguments for WolfSheepPredation model
- creating custom activation schedule by breed. This was done in order to emulate the procedures in the original model from netlogo
- modifying methods for the case when grass=True
- both wolves and sheep can die
- they only reproduce if they are still living
- added run_model method to show results in console, since I could get the visualization to run

Generalizing the schedule

Making the Breed-based scheduler generic, and making the model print
only if the verbose flag is set.