Add support for scaling options

[Chrezm]

Need to support

1. scaling_options: can be

• “width_smooth” scales the character so it fits the width of the viewport.
• “width_pixels” is for pixel art to ensure they scale properly.

2. scaling_presets: can be an arbitrary length list of objects that include as fields:

• “name”: This defines the name of this scaling present. This can be whatever you’d like but be sure to nest the name in quotation marks.
• “scale”: This defines the scaling of the sprite. The number to the side is taken from the client. I will explain how to get that in a moment.
• “vertical”: This defines the vertical displacement of the sprite. The number to the side is taken from the client. I will explain how to get that in a moment.

(descriptions taken from json guide)