allow reindex(new_axis)

[gdementen]

>>> arr = ndtest('time=1993..2017')
>>> arr.reindex('time=2015..2019')
TypeError: labels should be a sequence or a single int
>>> arr.reindex('time', 'time=2015..2019')
time  2015  2016  2017  2018  2019
       nan   0.0   1.0   2.0   nan
>>> arr.reindex('time', '2015..2019')
time  2015  2016  2017  2018  2019
       nan   0.0   1.0   2.0   nan

This is a bit annoying that the first version does not work.

[alixdamman]

Well, this will again make our API more complex and our users will again complain that the Tutorial/API Reference is unreadable.
But why not.