Update readme

[DanHickstein]

I noticed that the Readme still says that PyAbel required "PyAbel requires Python 2.7 or 3.3-3.5.". Clearly this hasn't been updated in a while.

Also, we might want to update the image with something more interesting, like Fig. 1 from the upcoming paper.

[stggh]

python version
Good point. IMO it would be nice to drop 2.7 (to save baggage) and move to 3.6+. We may then use f-strings for formatting.

image
Depends on "not published elsewhere" journal requirements.

Can PR #235 be merged? I would like to:
(1) Change three_point to Oliver Haas' #229 version
(2) Update the docs in linbasex (although, I have not yet started this process ...)

[DanHickstein]

I'd say that we give Py2.7 until 2020: https://pythonclock.org/

For the image, we could make some modifications to the image from the paper.

#235 is merged now! I haven't looked to carefully at Oliver Hass' version of three_point - what has changed? Maybe open a new issue on this when you have a chance.

New linbasex docs would be great.

[DanHickstein]

Reading through some journal policies, I would think that including a figure in the PyAbel readme would be acceptable, because the PyAbel github site is not peer reviewed and not copyrighted, so doesn't constitute prior publication. I'd like to include our image in the readme:

[DanHickstein]

Okay, these update have been made in #238! :) Closing this issue.