`|=` and `&=` fail

[Luca Bittarello]

Allegedly, because Fletcher doesn't support universal functions with keyword arguments.

MWE:

import fletcher as fr
import numpy as np

x = fr.FletcherContinuousArray([0])
y = np.array([False])

y |= x == 1

This error came to fore because it breaks replace (e.g., pd.Series(x).replace(0, 1)).

[Uwe L. Korn]

This sets kwargs = {'out': (array([False]),)}. I don't think we can actually support this as the fletcher array support nullability whereas the numpy.ndarray doesn't.