Make it possible to initialize array from dictionary values in Python 3

At the moment arrays can't be initialized from dictionary values in Python 3:

In [1]: import numpy as np

In [2]: d = {'a':1,'b':2,'c':3}

In [3]: np.array(d.values())
Out[3]: array(dict_values([2, 1, 3]), dtype=object)

and one has to instead explicitly convert to a list first:

In [4]: np.array(list(d.values()))
Out[4]: array([2, 1, 3])

It might be worth adding a special case in the initializer for the array to automatically do this conversion, since d.values() is a valid iterator?

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