Compute the angle (in degrees) between the line from (0,0) and this point and the line from (0,0) to
The function returns a value between 0 and 180 when the angle (in the direction from this point to
p) is clockwise, and a value between 180 and 360 when the angle is counterclockwise. The function returns
NaN if called from point (0,0) or if
p is (0,0).