Cone plotting incorrectly where [angle] >= Plunge

[OverCal]

When bidirectional = True, the shading of the cone is inverted where it crosses the stereonet boundary.

This error can be reproduced by using the example script with slight modification, where an angle of 59 will plot correctly and and angle of 60 will then invert:

import matplotlib.pyplot as plt
import numpy as np
import mplstereonet

Generate some scattered strikes and dips

num = 100
strike0, dip0 = 180, 60
strike = np.random.normal(strike0, 5, num)
dip = np.random.normal(dip0, 5, num)

Convert the strike/dip of the pole to plane to a plunge/bearing

plunge, bearing = mplstereonet.stereonet_math.pole2plunge_bearing(strike0, dip0)
fig, ax = mplstereonet.subplots()
ax.pole(strike, dip, color='k')
ax.cone(plunge, bearing, [60], linewidth=1, facecolor='blue', zorder=1, alpha=0.2, edgecolors='black', bidirectional=True)
plt.show()