made vt52 support actually setting the session ID

modules/drivers/vt52.lua

@@ -65,6 +65,7 @@ function tty(gA,sA,sI,fg,bg)
   end
  end
  spawn("tty["..tostring(sI).."]: "..gA:sub(1,8)..","..sA:sub(1,8),function() log(pcall(function()
+  os.setenv("sI",sI)
   while true do
    local csi = os.getenv("sI")
    log(csi)