Brping changes from pywcs to astropy
Use a warning instead of a print statement. Do not use deprecated io.fits.Header interface.
Data file has incorrect value of AXISCORR
Use warnings instead of print statements. printwcs() should print the PC matrix if available.
Fix typos
prin the PC matrix
Merge pull request #1099 from nden/wcs_d2im_2d

Bring changes from pywcs to astropy