Make robofish.evaluate usable from within python

It looks like robofish.evaluate is designed to be used from a shell. I think it would be useful to make it possible to use e.g. robofish.evaluate.evaluate_speed from python, to plot for example inside a notebook.

Right now I can not import robofish.evaluate after having done pip install robofish-io. (There is a related "TODO" comment in setup.py)

Additionally it would be nice if I could pass an axis to the evaluation function. Seaborn has this convention where you pass ax: matplotlib.axes.Axes as an optional keyword argument. If ax is None, seaborn calls matplotlib.pyplot.gca() internally. This way a user can create any kind of grid and tell the evaluation functions in which ax to plot, e.g. to show evaluate_speed and evaluate_turn side by side.