Sprite Packer helpers.
| atlasNames | Array of Sprite atlas names found in the current atlas cache. |
| kDefaultPolicy | Name of the default Sprite Packer policy. |
| Policies | Available Sprite Packer policies for this project. |
| SelectedPolicy | The active Sprite Packer policy for this project. |
| GetAlphaTexturesForAtlas | Returns all alpha atlas textures generated for the specified atlas. |
| GetAtlasDataForSprite | Returns atlasing data for the specified Sprite. |
| GetTexturesForAtlas | Returns all atlas textures generated for the specified atlas. |
| RebuildAtlasCacheIfNeeded | Rebuilds the Sprite atlas cache. |