[ofk123]

replacing #3

• great_circle_distance: limits the arcsin argument to <= 1 preventing errors for distance at identical points (or a rare anti-podal )
• AIS test data: the start speed was always random() * 0 / 102 which is always 0.0. Now it is a random value below SpeedOverGround.max_value.
• Fixed a few wrong return types in spatial.py