add 'columns' key to config

[tacman]

We need to require some column creation, not just match the csv / json column names.

tables:
   person:
       columns:
             - name: ageAtDeath
               calc: deathYear - birthYear
       

[tacman]

        rules:
            /ObjectID/i: id
            /BeginDate/: artistBirthYear
            /EndDate/: artistDeathYear
            /^Date$/: art_year
            /^Date_Acquired/: year_acquired
            /ConstituentID/: artist_id  # this rule ONLY applied in artwork.  Bug
        # could come from SQL or created during the import
        # if there's a match, move the data here.  Everything else goes in _attributes
        properties:
            - id:int
            - artistBirthYear:int
            - | 
                department: 
                    filterable: true
                    indexed: true
                    type: string
            - |
                birthYear: 
                    filterable: false
                    indexed: true
                    type: string
                    


        # additional columns
        columns:
            -   name: isAlive
                type: bool
                value: row.artistDeathYear == 0
            -   name: decade
                type: int
                value: row.year % 10 == 0
        indexes:
            - id|INTEGER
            - department
            - classification
            - art_year|INTEGER
            - date_acquired|DATETIME # hint only, but can get during in the sql https://stackoverflow.com/questions/17227110/how-do-datetime-values-work-in-sqlite
    #            - description|SEARCHTEXT,translatable