Many tests were added to arc_test.py.
I also added two methods to arc class: counter_clockwise and from_points_in_circle.
I modified _find_arc_intersection to consider arcs contained in the same circle, and modified includes_point too.
To circle class I added from_points_and_radius method.
To point class I added orthonormal_vector and mid_point methods.
Many tests were added to arc_test.py. I also added two methods to arc class: counter_clockwise and from_points_in_circle. I modified _find_arc_intersection to consider arcs contained in the same circle, and modified includes_point too. To circle class I added from_points_and_radius method. To point class I added orthonormal_vector and mid_point methods.