Stager Update to 1.2.1

[Data] Fixed an issue where pasted and duplicated objects were not properly saved and reloaded. [Data] Fixed an issue where decals could be corrupted and prevent files from loading again. The files will now load but the decals may be missing and need to be re-applied.

[Libraries] Fixed an issue where images were unable to be saved to Libraries.

[UI] Fixed an issue that allowed the environment light to be deleted when the environment light was selected, even if not the visible tab.

[Undo] Fixed an issue where reverting a file to a saved state was not undoable.

@JeanetteMathews tell if i miss something 😉