This would have been a complete fix in FMSLogo 7.7.0, but I have since changed ELLIPSEARC to calculate the angle of the sweep correctly, which made it so, in this implementation, the turtle either glides ahead or behind the drawn arc (but remains on the ellipse, which is still an improvement).
This also brings in a breaking change for when the third parameter is negative. The old ELLIPSEARC drew the arc on the opposite side of where the turtle is located. The new implementation draws the ELLIPSEARC sweeping in the opposite direction. The new behavior is more intuitive.
