Update commensurability warning

As discussed @zhubonan;

I think the check for the commensurability of the primitive and supercell in easyunfold is too strict. For instance, if one is doing easyunfold calculations for a SQS supercell which has been relaxed, and so has slightly different cell parameters, then this will print a warning saying the primitive and supercell are not commensurate which can be confusing for users. I know if the volumes are very different then this could impact the quantitative accuracy of the Brillouin Zone spacing, but I think this is likely a relatively minor effect in most use cases and we should have a certain tolerance for this (greater than the np.allclose default of 0.001%). Example of what I mean here:

image (21)

A relative tolerance of a couple percent should be fine? You likely know more about at what level of mismatch this would become significant enough to warn the user. Could have a two-level warning where if the match is close but not very good, it warns saying there will be some quantitative innaccuracies, or if very large mismatch then more severe warning

SMTG-Bham / easyunfold

Update commensurability warning #37