Save/Restore last view of a project

[dgud]

After loading a unsaved project during startup, and then creating a new project or loading another model
it should delete the previous unsaved object, because the user have had the chance to save it.

Now it is pretty irritating when you create a cube, autosave and close wings.
Then the cube will always be there until you save it somewhere, happens a lot
at least when developing for me.