Possible bugs with circle movement
In the Lua API it says that the functions get_angle_speed() and set_angle_speed() of circle movements are given in radians per second. But, if I am not wrong, they are given in degrees per second. (So, either we should change the Lua API, or we should fix this.)
I also have problems with the function set_initial_angle(), that does not admit values out of the range [0, 2*pi), if I am not wrong. For example, set_initial_angle(10) gives the error "Invalid initial angle: 10". (Also, if I write set_initial_angle(math.pi/2), it does not start with 90 degrees angle.)
I have not checked the rest of functions of the circle movement, so there could be more bugs.