Remove `info' table. The user is responsible for updating the checking
condition. Old style:
checkbox = {checked = true, label = "foo", align = "left"}
(...)
gui.Checkbox{info = checkbox}
New style:
checked = false
(...)
if gui.Checkbox{checked = checked, text = "foo", align = "left"} then
checked = not checked
end
Also note that `label' is renamed to `text'.
