Image tutorial notebook edit

Make the Image tutorial more friendly to people using the IPython notebook to follow along (avoid use of set_xxx functions, use arguments to imshow instead.)

Also:
- use scipy.ndimage for image resizing in last example (interpolation)
- minor grammar fixes
- add notes about keeping plt commands in one cell so that effects are shown.
I don't think the recommendation is to use that flag at all. I didn't think
the ipython would have made it available after the lessons leared about the
--pylab (which, along with the namespace issues, brings the exact issues
you raise). Even if ipython makes it available, I don't think we should be
recommending it.

On Fri, Nov 21, 2014 at 9:09 AM, Joris Van den Bossche <
notifications@github.com> wrote:

> In doc/users/image_tutorial.rst:
>
> >
> > -    $ipython
> > +    $ipython --matplotlib
>
> Just stumbled across this, and a small question: is there a reason you use
> (and thus recommend) --matplotlib intead of the cell magic %matplotlib. I
> personally think using the flag is always a bad habit, as using
> %matplotlib makes sure someone else can run your notebook as is (and does
> not need to start the notebook kernel in a specific way)
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/matplotlib/matplotlib/pull/3402/files#r20716168>.
>