Need for new warning level in hygiene tests

[mereolog]

There are hygiene tests, e.g., edmcouncil/fibo#1192, whose aim is not to identify modelling blunders in FIBO (like in https://github.com/edmcouncil/fibo/blob/master/etc/testing/hygiene/testHygiene0004.sparql), but to draw the attention of the developing team to possible cases of genuine issues there.

Thus, in order to demarcate the former from the latter I submit we need to add a new level of warning, say INFO, to hygiene tests.