Center Does Not Work as Expected with 2D Objects

[jmwright]

Consider the following:

el = cq.Edge.makeEllipse(x_radius = 1.0, y_radius = 10.0)
print(el.Center())

You would expect the center to be (0, 0, 0) because the ellipse is centered around the origin.

However, the result is:

Vector: (-1.0993893973079381e-16, -0.1653496405078786, 0.0)

I created a branch here which added the tolerance parameter in an effort to correct this. It did not work.

Per @adam-urbanczyk it seems like the class BRepGProp_Cinert does the actual work, and does not have a tolerance attribute. So we need to figure out the proper way to handle the fact that Center() works fine with 3D objects but not with 2D ones.