Phocube will export RA and declination planes even if the point is not on the...

Phocube will export RA and declination planes even if the point is not on the planet. Fixes #4446 (#657)

* Made it so that RA and Dec are added last.

* Updated code to be up to standards.

* Added RA and dec test.

* Updated history comment.

* Renamed test.

* Fixed typo in documentation

* Refactored code so that RA and dec are placed in the correct bands instead of moving them to the last two bands.

* Updated documentation, test now checks cube label.