revolve with angle=-180

[j042]

@clemens-fricke had an issue

import numpy as np
import splinepy as spp

cps = np.array([[0.0, 0.0], [0.0, height]])
cps_ = cps.copy() * -1
weights = np.ones([cps.shape[0]])
knots = np.repeat([0.0, 1.0], 2)
proto = spp.NURBS(
    degrees=[1],
    control_points=cps,
    weights=weights,
    knot_vectors=[knots],
)
rev_proto = proto.create.revolved(angle=-180)
rev_proto.show()

This is due to a wrong number of minimum knot span calculation. fix coming