Function for adding columns to table (i.e. to value subfield) was add(ScalarType). However add(Field) adds extra field to top-level structure. Rename former to avoid confusion and as more meaningful name. Update unit tests.
Function for adding columns to table (i.e. to value subfield) was add(ScalarType). However add(Field) adds extra field to top-level structure. Rename former to avoid confusion and as more meaningful name. Update unit tests.