Cinnamon: Adds hidden-buttons to list in applet settings

[claudiux]

Example in a settings-schema.json file:

"myList": {
        "type": "list",
        "default": [],
        "columns":  [
            {"id": "id", "title": "Name", "type": "string", "expand-width": true}
        ],
        "show-buttons": true,
        "hidden-buttons": ["+", "-", "edit"],
        "description": "My list"
    },

The "hidden-buttons" is an array that is [] (empty) by default.

This array can contain these values:

• "+"
• "-"
• "edit"
• "up"
• "down"

With the example above: "hidden-buttons": ["+", "-", "edit"], the user can not add, remove or edit rows to the list; the user only can move the items of the list.

TODO: Update documentation.