database mappings defined in json

[joaquimrcarvalho]

{
    "mappings": [
        {
            "name": "entity",
            "class": "entity"
        },
        {
            "name": "person",
            "class": "person"
        },
        {
            "name": "object",
            "class": "object"
        }
    ],
    "classes": [
        {
            "name": "person",
            "super": "entity",
            "table": "persons",
            "attributes": [
                {
                    "name": "id",
                    "column": "id",
                    "baseclass": "id",
                    "coltype": "varchar",
                    "colsize": 64,
                    "colprecision": 0,
                    "pkey": 1
                }
            ]
        }
    ]
}

[joaquimrcarvalho]

This would affect a few lines: https://github.com/time-link/timelink-kleio/blob/joaquimrcarvalho/issue16/src/gactoxml.pl#L1700-L1703

And two new predicates: mappings_from_json, classes_from_json.

[joaquimrcarvalho]

See https://www.mssqltips.com/sqlservertip/6270/save-sql-server-database-structure-as-json/.