It turns out Lua has been providing us this information all along! I'd
just not created the space on screen to show it. Make it persist better.
Kilo now no longer tracks its own status messages, which is a regression
in a rare condition.
One old drawback now has a new look. Before, we loaded definitions in
order, so global definitions had to exist before other global
definitions that used them. See window and grid in life.tlv. Now we load
definitions in reverse order, so initialization needs to change. Worse,
if we update window, we need to edit grid just to fix the order.
This implies that we can't yet optimize away bindings where there are no
new changes.
