Added SkyCoord.to_pixels_wcs
Added test for SkyCoord.to_pixels_wcs
switched to `to_pixel`
add cls keyword to pixel_to_skycoord
Added see also sections
added from_pixel and related tests
Added CHANGES.rst
Fixed docs typo
Fixed typo pointed out by @astrofrog

[ci skip]
Fix to properly include mode parameter

[ci skip]
Fix missing keyword name
Typo fix
Move wcs.utils imports to top-level
Merge pull request #3002 from eteq/add-pix-wcs-methods

Add  Skycoord.to/from_pixels_wcs