ENH - tolerance for orientation difference

[tiborauer]

This PR implements the tolerance for orientation difference as a soft-coded default setting

[gllmflndn]

Hello @tiborauer

Why not - in which particular context do you have to change the tolerance value?

I pushed a slightly modified version of your patch (tol_orient) in the development version of SPM: https://github.com/spm/spm/commit/5d32147955a57d252837f781433dfa17287a2bd3

[tiborauer]

Thank you for the patch and for letting me know about the developmental repo. I will use it for future PRs.

I used FSL for coregistration (BBR-based epi_reg) and did not reslice the images. I also applied the calculated transformation on other within-session images using spm_get_space. For some data, the discrepancy in the resulted orientations was between 1e-2 and 1e-3 (i.e. larger than 1e-4).