Create and Enum data type

[casperlehmann1]

Currently it is possible to create calculated columns in DAX as well as to add columns through Power Query. But for every column we add, our models get more bloated while the user interface gets more cluttered. I propose the addition of an enumeration type that is only evaluated at run time, this would reduce the file size of models by only requiring the developer to store references to values once. It would make possible to handle translation of the value in a secondary lookup table, thus eliminating the need for a complete re-evaluation of the column every time the lookup table is changed. Proposed interface: https://i.imgur.com/HCXgEy3.png