Fix for unclear resize() error message

When attempting to resize an array that is referenced elsewhere, the following error message appears:

```
In [4]: a.resize(3,2)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-4-265528f898a8> in <module>()
----> 1 a.resize(3,2)

ValueError: cannot resize an array references or is referenced
by another array in this way.  Use the resize function
```

This message confused me because it is not a proper sentence. It should say:
"cannot resize an array **that** references or is referenced by ..."

=> PR attached