Buttons display icons and text alongside each other, rather than vertically stacked

Property definitions

gtk $ GtkToolbarStyle :: both_horiz
	#Buttons display icons and text alongside each other, rather than vertically stacked
	new both_horiz `{ return GTK_TOOLBAR_BOTH_HORIZ; `}
lib/gtk/v3_4/gtk_enums.nit:321,2--322,52