Order of identifying fields

@peter_brueck has reported an issue with the order of identifying fields affected by the order of the columns in the preloading file.

This has not been intended to work that way - the order of columns in the preloading file should not be having any effect on the appearance of the cards in the assignment cards.

Yet, the bug that Peter has discovered may have been used and relied upon by some users, perhaps without knowing that this is not documented. As we are planning the strategy for the fix, please give a shout if you rely on the current behavior in your survey, as this may change soon.

Best, Sergiy