0.8.3 RC2 release

New feature:

• Supporting the save/restore instance state.
• Add onTapRegion, onDoubleTapRegion and onLongTapRegion methods to RegionLayer.OnSelectedRegionListener interface.

Breaking changes:

• Remove an argument MangaView from ContentLayer.onLongTap method.
• Listener interfaces have been moved in MangaView class.
• RegionLayer: Selectable region is only one where nearest to touched point.
• Change onTap|onDoubleTap|onLongTap event handling order.
  • So far: MangaView -> Pages -> Layers
  • Now: Layers -> Pages -> MangaView
• Optimize package structure.
  • *Layer classes have been moved into package .layer.
  • *Source classes have been moved into package .source.
  • and so on.