Allow separate description field for custom worksheets (in addition to the name field)

When worksheet fields are used in a formula, the text in the 'name' is used for that purpose as part of the syntax. Sometimes, it becomes necessary to change the name and that also means we have to change the formula wherever it is used. If there is a separate description field that can be used for other purposes and the name is used similar to the keys for other fields, it will make life much easier.