Numpy 1.20.0 causes problems for MaskedArrayWithLimits

[weaverba137]

Traceback from a recent test with Numpy 1.20.0:

______________________ TestPlots.test_masked_array_limits ______________________

self = <desiutil.test.test_plots.TestPlots testMethod=test_masked_array_limits>

    def test_masked_array_limits(self):
        """Test MaskedArrayWithLimits
        """
        from ..plots import MaskedArrayWithLimits
        data = np.arange(5.)
        mask = data < 3
>       ma = MaskedArrayWithLimits(data, mask, vmin=1.0, vmax=4.0)

py/desiutil/test/test_plots.py:46: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

cls = <class 'desiutil.plots.MaskedArrayWithLimits'>
args = (array([0., 1., 2., 3., 4.]), array([ True,  True,  True, False, False]))
kwargs = {'vmax': 4.0, 'vmin': 1.0}

    def __new__(cls, *args, **kwargs):
>       obj = super(MaskedArrayWithLimits, cls).__new__(cls, *args, **kwargs)
E       TypeError: __new__() got an unexpected keyword argument 'vmin'

py/desiutil/plots.py:157: TypeError

I suspect that the extra attributes could be added after the call to __new__().

[weaverba137]

After testing some testing, this seems to work:

        try:
            obj = super(MaskedArrayWithLimits, cls).__new__(cls, *args, **kwargs)
        except TypeError:
            # Numpy >= 1.20.0
            trimmed_kwargs = kwargs.copy()
            if 'vmin' in trimmed_kwargs:
                del trimmed_kwargs['vmin']
            if 'vmax' in trimmed_kwargs:
                del trimmed_kwargs['vmax']
            obj = super(MaskedArrayWithLimits, cls).__new__(cls, *args, **trimmed_kwargs)