Feature: An easy way to make a wcsaxes.WCS from an astropy.wcs.WCS object

[astrofrog]

The best way I can come up with is

ax = fig.add_subplot(1, 1 ,1 , projection=wcsaxes.WCS(astropywcs.to_header()))

Maybe this issue will solve itself when this is merged into astropy by just adding the required methods to the astropy WCS.
Until then (unless that happens soon), it would be nice to accept an astropy.wcs.WCS to initialize a WCS like so: wcsaxes.WCS(astropywcsinstance).

It's not so much the extra typing, but the fast that it took me almost an hour to discover this (or maybe I'm just dumb).

[astrofrog]

@hamogu - you can just do:

ax = fig.add_subplot(1, 1 ,1 , projection=astropywcs)

since Astropy's WCS knows of the existence of WCSAxes.

[astrofrog]

The wcsaxes.WCS class should actually be removed now that Astropy's WCS class works correctly.

[hamogu]

I just followed the examples in the docs...

[astrofrog]

@hamogu - ah, good catch, I wanted to leave some time after 1.0 was released then forgot about it :)

[astrofrog]

@hamogu - could you review this?

[hamogu]

Looks good to me; all the doc changes are relatively straightforward.
My only question is: What's the minimum version of astropy where this works?
installation.rst says "Astropy 1.0 or later". I don't know when the astropy WCS was changed to be compatible, but you probably know that on top of your head.

[astrofrog]

Astropy 1.0 is indeed when we added this.