Preserve data types when expanding table columns

With the function Table.ExpandTableColumn, a column with nested tables can be expanded. However, the data types of the columns of the nested tables are not applied to the new columns after expansion.
This behaviour is different from Table.ExpandRecordColumn, where data types of the nested records are applied to the new columns after expansion.
So this should also be possible with Table.ExpandTableColumn.

This will also further improve the "combine binaries" functionality that was already strongly improved with the November 2016 update of Power BI Desktop:
currently, you still have to change data types after combining binaries, while these data types may have been explicitly defined in the sample query that is created from "combining binaries".