remove the last screen and leave ScreenManager in a valid state, finishes #4107 and fixes #2655
remove the last screen and leave ScreenManager in a valid state, finishes #4107 and fixes #2655

matham/kivy,janssen/kivy,rafalo1333/kivy,andnovar/kivy,jkankiewicz/kivy,andnovar/kivy,kivy/kivy,Cheaterman/kivy,el-ethan/kivy,matham/kivy,kived/kivy,KeyWeeUsr/kivy,rnixx/kivy,akshayaurora/kivy,LogicalDash/kivy,jkankiewicz/kivy,manthansharma/kivy,darkopevec/kivy,rnixx/kivy,bionoid/kivy,akshayaurora/kivy,tony/kivy,aron-bordin/kivy,Cheaterman/kivy,kivy/kivy,rafalo1333/kivy,akshayaurora/kivy,kived/kivy,el-ethan/kivy,jkankiewicz/kivy,aron-bordin/kivy,janssen/kivy,tony/kivy,el-ethan/kivy,manthansharma/kivy,jegger/kivy,kivy/kivy,andnovar/kivy,inclement/kivy,bionoid/kivy,LogicalDash/kivy,darkopevec/kivy,Cheaterman/kivy,inclement/kivy,jegger/kivy,autosportlabs/kivy,KeyWeeUsr/kivy,matham/kivy,jkankiewicz/kivy,manthansharma/kivy,tony/kivy,janssen/kivy,Cheaterman/kivy,autosportlabs/kivy,darkopevec/kivy,autosportlabs/kivy,aron-bordin/kivy,jegger/kivy,LogicalDash/kivy,KeyWeeUsr/kivy,aron-bordin/kivy,LogicalDash/kivy,rafalo1333/kivy,KeyWeeUsr/kivy,matham/kivy,manthansharma/kivy,bionoid/kivy,jegger/kivy,inclement/kivy,kived/kivy,rnixx/kivy,darkopevec/kivy,bionoid/kivy,janssen/kivy