Graphics definition for a Prototype/Tree.
shadow is not specified, this has to have one more frame than
Shadow must have 1 less frame_count than
leaves (shadow.frame_count = leaves.frame_count + 1).
Only loaded if
shadow is present. Defaults to shadow.frame_count - 1.
Normal must have the same frame_count as
leaves (normal.frame_count = leaves.frame_count).
Overlay must have the same frame_count as
leaves (overlay.frame_count = leaves.frame_count). Won't be tinted by the tree color unless apply_runtime_tint is set to true in the sprite definition.