Added a new function to convert SkyCoord to pixel coordinates
Added missing imports
Add origin parameter
Added pixel_to_skycoord and unit test
Fix instantiation of SkyCoord
Implement mode option to select between full transformation (including distortions) and pure WCS. Extend tests.
Added changelog entry
Made has_distortion a property
Minor rewording
Updated changelog
Added missing @property
PEP8
Merge pull request #2885 from astrofrog/skycoord-to-pixel

Added a new function to convert SkyCoord to pixel coordinates