XOR operation of two circles are not correct

[carlos-adir]

The operation XOR between to circles does not give the correct result:

from compmec.shape import Primitive

circle_left = Primitive.circle(radius = 50, center = (-15, 0))
circle_right = Primitive.circle(radius = 50, center = (15, 0))
circle_xor = circle_left ^ circle_right 

Although using this operation we get the correct shape

circle_or = circle_left | circle_right
circle_and = circle_left & circle_right
circle_xor = circle_or - circle_and

The current implementation of __xor__ is theorically correct:

def __xor__(self, other):
    return (self - other) | (other - self)

[carlos-adir]

Using regular_polygon gives the correct result:

from compmec.shape import Primitive

circle_left = Primitive.regular_polygon(35, radius = 50, center = (-15, 0))
circle_right = Primitive.regular_polygon(35, radius = 50, center = (15, 0))
circle_xor = circle_left ^ circle_right

Probably it's a problem from the intersection between two bezier curves of degree 2.

[carlos-adir]

This should be solved by #67