Description

It would be really nice if indicate_error can also show error bars in x direction.

Steps to reproduce

import numpy as np
import proplot as plot

x = np.arange(10)
rng = np.random.default_rng()
y = rng.standard_normal((100, 10))

fig, ax = plot.subplots()
ax.plot(y, x, means=True)

Equivalent steps in matplotlib

errorbar has the xerr option to do this