static makeTranslation(tx, ty) {
        return new Mat3([
            1, 0, 0,
            0, 1, 0,
            tx, ty, 1,
        ]);
    }
@function makeTranslation
@memberof OpenSeadragon.Mat3
@static
@param {Number} tx The x value of the translation
@param {Number} ty The y value of the translation
@returns {OpenSeadragon.Mat3} A translation matrix