fix multi-tab: update title on tab switch
fix multi-tab: update title on tab switch

jmarshallnz/gummi,tonyolag/gummi-vim,tonyolag/gummi-vim,jmarshallnz/gummi,jmarshallnz/gummi,tonyolag/gummi-vim,jmarshallnz/gummi,tonyolag/gummi-vim