20191219 Update: GIF Support and Playback Rule

Version: 2.7.2 -> 2.8.0

• Added GIF support

  • Add and load GIF files as background

  • Add and load GIF files as Image Sticker

  • Options for GIF playback speed, reverse and ping-pong

Note: Large GIF files spend more memory than video files

• Added playback rules for application (Win)

• Added Moc information and log for Live2D Editor

• UI changes

• Bug fixes and code optimization