Add "skipping" options that protect some properties
Add "skipping" options that protect some properties

Each "skipping" option will protect one property of a data dictionary.
Additionally, `--updates-only` will block any new columns from being
added.

This commit also introduces a terminology change - "columns" was changed
to "entries". (Since data dictionary has one variable per row, the
previous code was explained in terms of "columns", where "column" really
meant the row entry for each variable. This was obviously confusing.)

sibis-platform/ncanda-data-integration,sibis-platform/ncanda-datacore,sibis-platform/ncanda-datacore,sibis-platform/ncanda-data-integration,sibis-platform/ncanda-datacore