Add an Aliases field

[matthewhorridge]

The Id is the primary key in a data dictionary. It is used to key fields in data files to the meaning of these fields in the data dictionary. Sometimes, there may be previous versions because of misspellings in the id name, versioning practices or simple name updates. A data dictionary should provide a way of tracking these. To do this we could an Aliases field as an optional field. This would accept multiple ids.