XTL_FALL_THROUGH

[solodon4]

I had to rollback XTL_FALL_THROUGH to 1 again because old Qua clauses seem to be putting break statements in the wrong place. See extractor.cpp for repro.

The value has to be 0 by default and macro probably deprecated (unless we want All Fit semantics too) because several novices made a mistake of not putting break at the end of the case clause effectively making the Match statement super slow because the code was needlessly checking all the predicates after the matching clause.