BottomCenter = function (gameObject, alignIn, offsetX, offsetY)
{
    if (offsetX === undefined) { offsetX = 0; }
    if (offsetY === undefined) { offsetY = 0; }

    SetCenterX(gameObject, GetCenterX(alignIn) + offsetX);
    SetBottom(gameObject, GetBottom(alignIn) + offsetY);

    return gameObject;
}
Takes given Game Object and aligns it so that it is positioned in the bottom center of the other.

@function Phaser.Display.Align.In.BottomCenter
@since 3.0.0

@generic {Phaser.GameObjects.GameObject} G - [gameObject,$return]

@param {Phaser.GameObjects.GameObject} gameObject - The Game Object that will be positioned.
@param {Phaser.GameObjects.GameObject} alignIn - The Game Object to base the alignment position on.
@param {number} [offsetX=0] - Optional horizontal offset from the position.
@param {number} [offsetY=0] - Optional vertical offset from the position.

@return {Phaser.GameObjects.GameObject} The Game Object that was aligned.