Adds customData feature

[mathieuanthoine]

Adds the support of Flash Pro persistent Data in the JSON. Adds persistent data on MovieClip, Sprite, Keyframes and you will get them in the JSON in the parameter named "data" of each entity. The data property is an object that can contain custom data as many as you want, with correct types (string, integer, number, array of integers and numbers)

At the moment, the AS3 runtime has no direct access to these data. flump-pixi-runtime(haxe) will support it soon.

To simply edit persistent data, install the Persistent Data Panel : https://github.com/mathieuanthoine/AnimateCCPersistentDataTools

[mathieuanthoine]

customData support available on pixi-flump-runtime