Set order of axes on loading FITS files

[malikolivier]

Problem

How to define the order of axes on loading a FITS file?

Possible solutions

• Load axis from the FITS file in the provided order (as is)
  • That's more or less what is done now.
• Set axis in a specific order to be defined from the CTYPEn value of a FITS header
  • Define rules such as WAVE always before DEC--TAN, DEC--TAN always before RA---TAN, etc.
• Allow the user to load the axes in an arbitrary order

Please voice your opinion regarding how we should solve this problem. Especially, it would be interesting to know if there is even a problem to begin with in the current implementation.