Correct oblique

[Gab-D-G]

No description provided.

[Gab-D-G]

This will likely create conflicts with #326 , but will be easily resolved.

[Gab-D-G]

It would be ideal to add an automated check on whether the data is oblique before applying the correction, to prevent converting images which don't need it. Any input on this @grandjeanlab or @gdevenyi (in relation to #160)?

[gdevenyi]

I would rather this remain manual.

I'm in favour of adding a check for oblique data and erroring out, recommending the user investigate its origin and explain the use of the deoblique option.