ENH: Improve the alignment of recarray.__repr__

[eric-wieser]

Previously, the prefix argument was not being passed to array2string

Before:

>>> r
rec.array([[(1, 2), (3, 4), (5, 6)],
 [(6, 5), (4, 3), (2, 1)]], 
          dtype=[('a', 'i1'), ('b', 'i1')])

After:

>>> r
rec.array([[(1, 2), (3, 4), (5, 6)],
           [(6, 5), (4, 3), (2, 1)]], 
          dtype=[('a', 'i1'), ('b', 'i1')])

[charris]

Thanks @eric-wieser .