Merge pull request #34 from astrojuanlu/fix_deprecated_import-take-3

Iterable imported from collections.abc (take III and final)

quaternions/quaternion.py

@@ -1,6 +1,6 @@
 import functools
 import numpy as np
-from collections import Iterable
+from collections.abc import Iterable
 import numbers
 
 from quaternions.utils import (covariance_matrix_from_angles, sigma_lerner, xi_matrix)