layout_mode={
 obscured=0,  -- for wells
 vertical=1,  -- for conventional slots
 -- todo: sideways
}

layout=klass()
function layout:init(x,y,mode)
 self.x=x
 self.y=y
 self.mode=mode
end

function layout:place_card(i)
 if (self.mode==layout_mode.obscured) return self.x,self.y
 if (self.mode==layout_mode.vertical) return self.x,self.y+(i-1)*6
 assert(false,"unexpected mode: "..self.mode)
end