Comparator: Changing one column name and dropping one leads to changing both into the new name.

If you have a table and in a new version rename one and drop another column both of exactly the same definition, the comparator will errorusly optimize the one to rename both columns to the new one.

In these cases where it is not detectable which is the renamed and which the dropped it should drop both columns and create the new one. The user has to optimize this himself.